Offensive realism:

  Indeed, he declines to classify states as more or less aggressive on the basis of their differing economic and political systems. His theory of great power relations - which he calls "offensive realism" - makes only a handful of assumptions about great power conduct, "and these assumptions apply equally to all great powers."
  &
  Offensive realism is a challenge to the two other predominant "realist" theories of great power relations: "Classical realism," set forth by Hans Morganthau in "Politics Among Nations," and "defensive realism," set forth by Kenneth Waltz in "Theory of International Politics." It is, of course, also a challenge to modern liberal sensibilities that are at odds with all the amoral realist views.
  &

States have a "will to power" - a "limitless lust for power" - hardwired into them  because of the ambitions of their leaders.

  Classical realism is based on human ambition.  States have a "will to power" - a "limitless lust for power" - hardwired into them  because of the ambitions of their leaders. They constantly look for opportunities to take the offensive and dominate other states.
  &
  As Mearshiemer points out, this view provides no room for powerful states - like the British Empire in the 19th century and the United States in the 20th century - that are satisfied and seek primarily to defend the status quo. It recognizes the role of fear, but treats that as "a second-order cause of state behavior."
  &

Wars are largely the result of uncertainty and miscalculation, and most often impose large burdens and offer few gains even when successful. Fear for loss of incumbency - for loss of power already held within a nation - favors the maintenance of peace between great powers.

  Defensive realism, also referred to as "structural realism," does not assume inherent aggression. The will to survive means that security is the predominant concern. The structure of the international system forces great powers to pay attention to the balance of power, and to seek to enhance power because "power is the best means to survival." But aggression is usually a mistake, because it causes other states to ally against you to balance out your power - and involvement in actual conflict carries the most significant threat to survival.
  &
  Indeed, great power balancing and the advantages usually enjoyed by the military and diplomatic defense over offense "should discourage great powers from pursuing aggressive strategies and instead make them 'defensive positionalists.'" Preserving power, rather than increasing it, should be the predominant strategic objective, according to defensive realism. Wars are largely the result of uncertainty and miscalculation, and most often impose large burdens and offer few gains even when successful. Fear for loss of incumbency - for loss of power already held within a nation - favors the maintenance of peace between great powers.
  &

"Great powers behave aggressively not because they want to or because they possess some inner drive to dominate, but because they have to seek more power if they want to maximize their odds of survival."

  Mearshiemer's offensive realism is also based on the inherent fears for survival that arise in the anarchic international arena. However: "Great powers behave aggressively not because they want to or because they possess some inner drive to dominate, but because they have to seek more power if they want to maximize their odds of survival."
  &
  Geography does impose limits on this drive for power. Large distances and, especially, large bodies of water, make it difficult to project power - to move and maintain large armies. This is not an obstacle that safeguards smaller powers from great power aggression. However, it does safeguard distant great powers from each other, and reduces the fears aroused among distant great powers and great powers divided by major water barriers like the English Channel and the Atlantic Ocean.
  &
  Thus, the English Channel not only safeguarded England from European armies, it also safeguarded Europe from English power during the 19th century period of English superiority. Similarly with the United States today. The United States is satisfied with regional hegemony in the Western Hemisphere, which is easily maintained even over great distances and oceanic lines of transportation because there are no other great powers in the Western Hemisphere. But the U.S., like England, is content to play a balancing role elsewhere - content to favor the status quo. Thus, no nation content to live peacefully within its borders need fear aggression from these "offshore balancer" powers.
  &
  Mearsheimer debunks the notion that victory in war seldom offers benefits. He points to the successful 19th century conflicts that resulted in the unification of the Italian and German states, and the benefits Hitler was gaining from WW-II  while he was winning. In the United States, the Union was successfully preserved during the Civil War, and a vast western empire was wrested from the Great Plains tribes and Mexico by means of successful conflicts.
  &
  The United States - with its English ally - having achieved as much power as they can - given the geographic realities - are now peaceful status quo states concerned only with preventing any other great powers achieving the kind of regional hegemonic power that might threaten their current level of security. They may talk in moralistic and liberal terms, but they respond to the dictates of offensive realism.
  &

The question is whether simplification has gone too far - whether elements that are in fact importantly "outcome determinative" have been simplified out - thus crossing the line into invalidity.

Like the blind men examining the elephant, these theories are all correct - but only about the part of the problem they concentrate on.

Bismarck even then demonstrated a keen sense of the "soft power" factors in international power politics.

  As with all general theories, Mearsheimer has greatly simplified reality to facilitate understanding. The question with all of these efforts is whether simplification has gone too far - whether elements that are in fact importantly "outcome determinative" have been simplified out - thus crossing the line into invalidity.
  &
  All of these realist theories are like the blind men examining the elephant. They are correct - but only about the part of the problem they concentrate on. Each identifies real factors in great power interrelations - but omits or minimizes others - some of which are substantially outcome determinative and thus must be accounted for before any theory of international power politics can claim validity.
  &
    Great power politics are influenced by both security fears and by the ambitions of their leaders. They are influenced by the power available and a variety of limits to the application of that power. Moreover, the fears and ambitions of leaders - and the limits to power - are in fact heavily influenced by political systems and the levels of popular support that can be generated by different governments for different policies - and the moral sensibilities dominant in each nation.
  &
  Thus, all three realist theories and the general liberal alternative are correct in part but invalid overall.

  Bismarck is properly cited and quoted by Mearsheimer concerning the security needs that drove his successful foreign policy of conquest and power enhancement. No statesman ever had a firmer grasp of the realities of great power international relations. 

  However, it was also Bismarck who shrewdly noted that the fact that the Americans and British spoke the same language was the most important political fact of the age. Bismarck even then had a keen sense of the "soft power" factors in international power politics.

Fear and loathing:

Magnanimity towards defeated adversaries and good will towards peaceful states has been a key to U.S. victories during the 20th century.

History does indeed open windows on the future. However, the past never repeats precisely. Examples taken from the 19th and 20th century age of European imperialism are unreliable guides to 21st century tendencies.

  A potentially dominant great power - a potential hegemonic great power - almost naturally creates fear and loathing in other great powers.

  "Because a state's intentions are difficult to discern, and because they can change quickly, rival great powers will be inclined to assume the worst about the potential hegemon's intentions, further reinforcing the threatened states' incentive to contain it and maybe even weaken it if the opportunity presents itself."
  &
  Avoidance of fear and loathing has been a spectacularly successful strategy for the United States. Magnanimity towards defeated adversaries and good will towards peaceful states has been a key to U.S. victories during the 20th century.

  A substantial portion of the book is dedicated to analysis of the historic record of the last two centuries to show how - with one exception - the conduct of great power foreign policy can be explained by the concepts of offensive realism.

  Mearsheimer is, of course, correct in examining the past to derive trends that will influence the future. History does indeed open windows on the future. However, the past never repeats precisely. Examples taken from the 19th and 20th century age of European imperialism are unreliable guides to 21st century tendencies. You can't succeed merely by planning to fight the last war over again - and, today, the changes come faster than ever.

  The one major historic exception that Mearsheimer recognizes was the failure of Wilhelmine Germany to strike during the 1905-1907 period when Russia was greatly weakened by its conflict with Japan.

  There are other such anomalies. Mearsheimer glosses over the failure of Soviet Russia to join Great Britain against Germany after the fall of France. However, if Germany had defeated Great Britain - as widely believed at that time - Russia would have been left totally alone to face both Germany in Europe and Japan in Asia. Also, offensive realism doesn't explain why the U.S. has not absorbed Canada - a resource rich, sparsely populated plum vulnerable across a long undefended border.

The limits to power:

Unless an occupying power is willing to act with utter ruthlessness - unless it is identified with the clear evil of a Hitler or Stalin - an occupation can become too expensive and difficult to maintain.

A higher moral understanding served the U.S. well in the manner in which it used its brief occupation of its defeated WW-II adversaries to influence their postwar political orientation.

The levels of ruthlessness sustainable over time in the exercise of power also provides an objective standard by which to distinguish especially dangerous and evil nations from others - and undermines the amoral classical and offensive realist approaches.

  Here, oversimplification leads to inconsistency. Even after territory is conquered, there is the problem of occupation. Unless an occupying power is willing to act with utter ruthlessness - unless it is identified with the clear evil of a Hitler or Stalin - an occupation can become too expensive and difficult to maintain - as Mearsheimer inconsistently concedes elsewhere in his book.
  &
  France thus could not maintain its occupation of the Rhineland after WW-I, despite its fears concerning a future resurgence of the German threat. Since they were not welcome, the French simply could no longer afford to stay.
  &
  After the passing of Stalin, even the Soviet Union - as soon as it was no long willing to act with utter ruthlessness - found that occupation of unwelcoming states was a losing proposition. It wound up heavily subsidizing all but two - Iraq and Libya - of its many client and occupied states. It ultimately had to abandon its occupation of Eastern Europe and areas of Central Asia, despite the weakness of those states and the ease of occupation of most of them.
  &
  Occupation is, of course, no problem during wars that coalesce generally willing ethnic populations into national units. It is also no problem once an indigenous population is practically wiped out and replaced - as occurred in the American west. It may also be no problem if a small indigenous population is simply submerged by an influx of people from the conquering nation.
  &
  Thus, for states unwilling to be utterly ruthless - for states that are not so "evil" that they can wipe out entire populations to maintain control - there are definite and obvious limits to power that Mearsheimer totally ignores.
  &
    For example, after ruthlessly conquering its western territories, the U.S. similarly ruthlessly conquered the Philippines. However, it quickly realized it could not maintain an occupation of so populous a nation - that occupation was a wasting asset for the United States which was already rapidly developing along liberal moral lines - and that 19th century imperialism was not an option for the 20th century U.S. no matter how militarily weak the occupied territory. This higher moral understanding served the U.S. well in the manner in which it used its brief occupation of its defeated WW-II adversaries to influence their postwar political orientation.
  &
  Of course, the levels of ruthlessness sustainable over time in the exercise of power also provides an objective standard by which to distinguish especially dangerous and evil nations from others - and undermines the amoral classical and offensive realist approaches.

No nation other than the U.S. is currently capable of affording even peacetime levels of modern weaponry.

  Mearsheimer recognizes limits to power, and deals with several of them. The costs of Pyrrhic victories - the restraining influence of nuclear weapons - and geographic distance and great water obstacles - are all acknowledged and included in his theory. Many factors, including the extent to which resources are dedicated to social welfare purposes, can limit the resources that can be mobilized for military purposes.
  &
  Inconsistently, Mearshiemer also recognizes that the cost of modern weaponry and warfare forces political leaders to finely balance their military and imperial expenditures against the resulting financial drain that can ultimately undermine both economic and military power. This acknowledgement contradicts his assertion that  the heavy military expenditures of conquest and occupation are not necessarily an economic burden. (See, "The benefits of military victory," below.)

  Victories can now more readily prove Pyrrhic because of economic costs as well as human costs - as Great Britain learned during its uniformly victorious major 20th century conflicts. Indeed, no nation other than the U.S. is currently capable of affording even peacetime levels of modern weaponry. The financial drain of empire and armaments caused the Soviet Union to collapse far more rapidly than it otherwise would have under the simple weight of socialist rigidity and mismanagement.
  &
  It is thus strange that Mearsheimer fails to recognize the differing costs and difficulties that various nations experience in maintaining an occupation. These costs are real - even for a Hitler.

Wilhelmine Germany could never have hoped to derive power from imperial holdings that might ever have come close to balancing out the cost of adding England to its enemies.

  The many economic benefits and military units obtained from occupied Europe during the initial years of Hitler's WW-II conquests are eagerly listed. However, omitted are such huge liabilities as the need to deploy 60 divisions in occupation duties, and the unreliability of military units from unwilling allies that constantly embarrassed German battle plans and drained available German forces.
  &
  If Hitler were truly influenced primarily by security fears concerning Russia rather than by ambitions for conquest, he would have been far wiser to ally himself with Britain and France and sustain Poland as a buffer. Like Bismarck, he should have confined his conquests to a gathering in of welcoming German populations.

  The not very persuasive answer to this objection is that leaders are prone to many miscalculations. Correctly, Mearsheimer notes that even the most important decisions have to be made on inherently imperfect information. He acknowledges that political leaders fear the uncertainties and costs of military confrontation and war, but asserts that they nevertheless frequently miscalculate the gains and losses achievable by power political actions. Indeed, because of their fears, they frequently overreact to perceived threats - generating costly and destabilizing arms races - and even precipitating vast conflicts.

  Nevertheless, it is simply not credible to minimize the role of ambition in the aggressive tendencies of Napoleon and Hitler - or even of Kaiser Wilhelm II. Mearsheimer correctly notes that the English Channel eliminated England as a direct threat to Germany, and that England had at the end of the 19th century apparently intractable differences with Russia and France all around the globe. Why, then, would Germany build a Navy that could threaten England and drive England into the arms of France and Russia?
  &
  The German navy was designed specifically to fight in the North Sea - its only practical purpose was to fight England. It was of little use against France, and no use against Russia. If fear rather than imperial ambition was the only or predominant driving force of Wilhelmine policy, assuring England as an ally would have been the obvious - and clearly achievable - alternative, and would not have diverted such huge resources from the buildup of the armies that Germany would need to face great power continental adversaries. Nor could Germany hope to derive power from imperial holdings that might even come close to balancing out the cost of adding the British Empire to its enemies.
  &
  If fear rather than ambition were the only or predominant influence, we are not here talking about mere miscalculation but of stupidity on a scale so colossal as to be totally untenable.

  Other current limits to power that Mearsheimer excludes include:

• The reduction in average family size in all the great powers: Nations where single son and single child families predominate cannot sustain aggressive policies that might result in conflicts costing hundreds of thousands of casualties.
• The spread of democracy: Democratic politics does create a natural bias against war. War offers elected politicians little personal political advantage - diverts resources that might otherwise be spent in pleasing constituents - and poses additional disagreeable economic and military threats to incumbency.
• Liberal sensibilities: Great powers that realize they cannot play the old imperialist games - that realize they cannot sustain the occupation of unwelcoming territories - will always have a strong interest in combining to oppose any great power that thinks it can. They will always have a strong interest in sustaining the status quo against any aggressor state.
• Capitalist alternatives: All nations heavily engaged in international commerce have shared interests in a legally ordered and physically secure world. Only capitalist states can today achieve great power status, and capitalist states always have economic alternatives for the enhancement of power and security. The U.S. can trade with Canada and invest in Canada - it doesn't have to occupy it. A truly capitalist China might come to the same conclusions about the resources of the South China Sea - and Siberia.

For limited conflicts involving decades of confrontation, the successful husbanding of financial and economic resources can become the difference between victory and defeat - as it was in the Cold War.

The primary political interest in democracy is incumbency - and nothing threatens incumbency as much as a costly, uncertain major war.

  A more prosperous China or Russia may indeed - at some future time - choose to militarily confront U.S. interests. However, the burden of major armaments expansion is a powerful deterrent factor that must not be overlooked.  They would face the dilemma of major armaments programs. The more that economic resources are dedicated for armaments today - the less economic resources will be available tomorrow.
  &
  This makes no difference in all-out unlimited conflicts likely to be resolved in a few years. However, for limited conflicts involving decades of confrontation, the successful husbanding of financial and economic resources can become the difference between victory and defeat - as it was in the Cold War.
  &
  Democracy does make a difference. The primary political interest in democracy is incumbency - and nothing threatens incumbency as much as a costly, uncertain major war. Nothing so draws government resources away from the domestic projects desired by the electorate.
  &
   All democracies quickly reorient their budgets towards domestic programs as soon as conflict ends.  The fabled "military-industrial complex" in fact cannot exist without a visible external threat. 
  &
  Furthermore, the foreign policies of democracies are more consistent than those of autocratic governments, since they are less likely to significantly change with a change of ruling party. They are more likely to be guided by consistent commercial interests.

There have, in fact, been many examples during the last two centuries that fit well with offensive realism.

  However, for military adventures based on ambition or questionable assertions of national security - and for efforts to justify long term occupation of conquered territories - democratic politics and liberal sensibilities come heavily into play as restraining influences.

  However, the conduct of Prussia, Japan, and the Soviet Union during their empire building period fits well into the theory of offensive realism. At those times, these states clearly acted as offensive realists. The conduct of the U.K. and the U.S. during their empire building period also fits well. Germany, Japan and the Soviet Union were forced by defeat to surrender imperial ambitions, and Britain was forced to surrender its empire by a series of Pyrrhic victories. These are five of the great hegemonic and potential hegemonic powers analyzed by Mearsheimer.

  The U.S. simply decided that it was big enough, and abnegated its last imperial holdings and ambitions without being forced to do so. It survives as a great hegemonic power, while the others do not.
  &
  Interestingly, this was the strategy adopted by Bismarck for Germany. He knew precisely how far Prussia/Germany could profitably expand - and when further imperial ambitions were unwise. His successors, however, lacked this insight - and were driven by great ambitions.. 

  Mearsheimer recognizes the reality of goals that have little direct influence on security - goals based on religion, ideology, ethnic identity, and concerns for human rights. However, he dismisses liberal notions of the restraining influence of morality and modern liberal sensibilities. When national security is perceived to be at stake, he correctly notes that liberal sensibilities are quickly abandoned.
  &
  Thus, the U.S. had no trouble allying itself with Stalin during WW-II - or tilting in favor of Saddam Hussein during the Iran-Iraq conflict - or allying itself or cooperating with a host of noxious despots - including ultimately China's Chairman Mao - during the Cold War.

  However, for military adventures based on ambition or questionable assertions of national security - and for efforts to justify long term occupation of conquered territories - democratic politics and liberal sensibilities come heavily into play as restraining influences. Democratic electorates will not long support such efforts, and capitalist interests will oppose the costs.

Wealth and power:

&

"I define power largely in military terms because offensive realism emphasizes that force is the ultima ratio of international politics."

Mearsheimer concentrates on the size of the army - the only military arm capable of taking and holding ground.

  However, he recognizes other factors - factors not readily quantifiable - that can come into play to alter the apparent balance of power. Among others, "strategy, intelligence, resolve, weather, and disease" can determine military outcomes.
  &
  "Mobilizable wealth" is the resources - both population and economic - available to build and support military forces. GNP is the most commonly used indicator, but doesn't capture differences in mobilizable wealth. GNP does not reflect access to cutting edge technology vital for modern armaments. GNP becomes a good measure only when comparing states at similar levels of economic development. Also of importance in the long run is the extent to which defense spending can be pursued without undermining economic growth or even the ability to sustain armies already raised.

  "All great powers are wealthy states, [but] not all wealthy states are great powers." (But the Soviet Union was never really "wealthy" in relation to the size of its population. It was a great power solely because of the extent to which it dedicated its economic potential to military and imperial expenditures - an extent that was ultimately disastrously unsustainable.)

  Another variable is the type of expenditures - especially the amount spent on the army and the ability to project power. A lengthy segment of the book is dedicated to arcane arguments over the relative importance of various kinds of land, naval and air power.
  &
  British power was concentrated in its navy to protect its worldwide commercial and imperial interests, so its small army was never a threat to achieve hegemonic power over Europe. Mearsheimer concentrates on the size of the army - the only military arm capable of taking and holding ground. He views airpower and naval power as playing just a secondary supporting role to the army.
  &
  It is for this reason, according to Mearsheimer, that Western Europe allied itself with the U.S. against the Soviet Union, even though the U.S. was clearly the stronger power. Because the Soviet Union had the more powerful army and existed on the European continent, the threatened European powers "considered the Soviet Union, not the United States, to be the most powerful state in the [European] system."

    However - especially in an age of precision munitions - control of the air is increasingly the tactical equivalent of control of the high ground. Even as early as 1944 during WW-II, large German formations were prevented from effectively maneuvering because of Allied control of the air over western battlefields.
  &
  Control of the seas directly impacts the ability to sustain the economic production needed for all military activities. Control of the seas is more important for maritime nations than continental powers, but effective naval blockades can have an adverse impact on any nation. Moreover, only the predominant naval power can shape the laws of the seas in favorable ways for its commerce, ultimately strengthening its economy and enabling it to field large armies and/or support the larger armies of its continental allies.
  &
  But Mearsheimer is clearly correct on one key factor -- even today, it is still true that only the grunt on the ground can take and hold territory.

Nuclear weapons make unlimited wars of conquest unlikely between great powers, but have not hindered conflicts with limited objectives in peripheral areas.

  Furthermore, the ability to mobilize wealth for war purposes varies for a wide variety of reasons. Surprisingly, militant Nazi Germany was far less efficient at mobilizing its economic power for WW-II production than its major adversaries - the United States, Great Britain, or the Soviet Union.
  &
  Mearsheimer concludes:

  "Armies, along with their supporting air and naval forces, are the paramount form of military power in the modern world. Large bodies of water, however, severely limit the power projection capabilities of armies, and nuclear weapons markedly reduce the likelihood that great-power armies will clash. Nevertheless, even in a nuclear world, land power remains king."
- - -
  "[Thus, the] most dangerous states in the international system are continental powers with large armies. In fact, such states have initiated most of the past wars of conquest between great powers, and they have almost always attacked other continental powers, not insular powers, which are protected by the water surrounding them."

  Nuclear weapons make unlimited wars of conquest unlikely between great powers, but have not hindered conflicts with limited objectives in peripheral areas.
  &

Hegemonic power:

  Since no state can control the entire world, great powers strive to gain hegemonic status in their regions. Today, only the U.S. has achieved this status - largely because of the absence of any other great powers in the Western Hemisphere. It ardently strives to prevent any other great power from achieving similar status in either Europe or Asia.
  &

Ultimately, the maintenance of an army that is dominant within its region, and the establishment of nuclear superiority or at least parity, are basic objectives.

  To do this, the U.S. seeks alliances with the weaker great powers. Like Great Britain before it, it provides enough support to enable the weaker continental powers to sustain themselves against stronger neighbors. The strategies available are containment or balance of powers. Balance of powers is the preferred strategy, because if successful it is less costly. However, if balance of powers fails, a direct and costly effort at containment becomes required.

  "In essence, regional hegemons act as offshore balancers in other areas of the world, although they prefer to be the balancer of last resort."

  The reason that the U.S. does this is because it fears that another regional hegemonic state that equals its own power might successfully challenge for influence in the Western Hemisphere, undermining U.S. hegemonic status and security.
  &
  It might also challenge U.S. interests in more distant regions of the world. A superior economy with access to other wealthy markets and strategic supplies - principally oil - is a second vital strategic factor that must be protected, since this ultimately determines military potential.
  &
  Ultimately, the maintenance of an army that is dominant within its region, and the establishment of nuclear superiority or at least parity, are basic objectives.
  &

The benefits of military victory:

Mearsheimer overlooks the costs of an unwelcome occupation of defeated adversaries, and emphasizes only the benefits.

For the Soviet Union, its empire and almost all its client states became a financial millstone around its neck.

  However, Mearsheimer casually dismisses the economic limitations of military force with a deplorable display of ignorance of basic economics. This enables him to overlook the costs of an unwelcome occupation of defeated adversaries, and to emphasize only the benefits. His shallow economic assertions indicate uncritical acceptance of some Keynesian stupidities.
  &
  First, he invokes some special cases as proof of the benefits of conquest. Prussia under Bismarck unified the Germanic peoples by conquest. However, Bismarck wisely limited his conquests to Germanic states. The United States in the 19th century conquered its western territories by means of a war of annihilation - something most great powers would not consider today.

  Conquest can be profitable if the conquering state is prepared to be totally ruthless in dealing with the conquered peoples, or is for one reason or another  welcomed by the conquered peoples and willing to give them equal or near equal status within the empire.
  &
  Genghiz Khan could conquer the civilized world, because nobody would dare to refuse to cooperate - and because he tolerated differing cultures and religions and opened the trade routes that permitted most to flourish within his empire. The Roman Republic famously made staunch allies of the other tribes it initially conquered on the Italian Peninsula - and was also prepared to act ruthlessly to put down rebellion. The Spanish annihilated the Incas and Aztecs.
  &
  Israel has neither annihilated its Palestinian adversaries nor used its occupation to arrange a satisfactory settlement. Mearsheimer contends that it improved its strategic position by its victory. Victory was certainly more favorable than defeat. Unsurprisingly, however, its occupation of Palestinian lands has been a wasting asset, and is today an increasing liability despite Israel's vast predominance of military power.
  &
  It has in fact been widely accepted that military occupation is a wasting asset unless the occupation is either a liberation or is totally ruthless. To repeat: The U.S. wisely recognized this fact after WW-II, and prepared the conquered Axis nations to resume their status as autonomous states and equal participants in the commercial world - and as allies in the Cold War. France was unable to do this in its failed occupation of the Rhineland after WW-I, and the Soviet Union ultimately failed in Eastern Europe and Central Asia. Indeed, for the Soviet Union, its empire and almost all its client states became a financial millstone around its neck.

  Then, Mearsheimer gives us this statement:

  "Moreover, little scholarly evidence supports the claim that high levels of defense spending necessarily hurt a great power's economy. The United States, for example, has spent enormous sums of money on defense since 1940, and its economy is the envy of the world today."

Only in the last half of the 1990s - well after the Cold War was over and defense spending had declined to the lowest levels since before WW-II - did the U.S. economy achieve full employment and rates of growth that are the envy of the world.

  Mearsheimer is here in denial about some very obvious facts. The U.S. accumulated vast financial resources as a result of its late entries into both WW-I and WW-II. This included over 60% of the world's monetary gold.
  &
  During the first two decades of the Cold War, the U.S. prospered despite heavy defense and other government spending - but was only able to maintain the value of the dollar and avoid heightened rates of inflation by expending significant sums from its huge gold and other financial reserves. It was obvious that this could not continue, and the publisher of FUTURECASTS online magazine pointed this out in a book presciently entitled "Dollar Devaluation" - published in 1967 - that accurately predicted the troubles that would afflict the U.S. in the 1970s.
  &
  Indeed, the financial reserves were in fact run down by 1972 - the dollar was devalued - and the nation was afflicted with vicious swings of the business cycle, double digit inflation and unemployment and basic interest rates at about 20%, ending in the depression of 1980-1982. Indeed, the economy functioned below par for another 15 years - leading many to assert that the U.S. was in decline.
  &
  Only in the last half of the 1990s - well after the Cold War was over and defense spending had declined to the lowest levels since before WW-II - did the U.S. economy achieve full employment and rates of growth that are the envy of the world.

  Mearshiemer continues:

  "The United Kingdom had a huge empire and its economy eventually lost its competitive edge, but few economists blame its economic decline on high levels of defense spending. In fact, the United Kingdom historically spent considerably less money on defense than did its great-power rivals."

The denial of the inherent financial burdens of military spending is a key fallacy in this theory

  The ability to defend itself with a navy so that it did not have to maintain a large expensive army was certainly a great economic advantage for England. And there were certainly other factors involved in England's financial and economic decline during the 20th century - including bloated levels of government domestic spending, a growing array of economic rigidities, and disastrous experiments with socialism.
  &
  However, you have to be blind to ignore the financial drain England suffered during WW-I -- or how fast WW-II expenditures essentially destroyed its remaining financial strength and forced it to run begging for aid to the United States. Similarly, by the end of the Cold War, the U.S. had to beg its allies for financial aid to fight a minor conflict in the Persian Gulf against a fourth rate power. France actually had to reduce military expenditures in 1938 on the eve of WW-II for lack of financial resources.

  Mearsheimer is certainly right in arguing that the Soviet economy had "profound structural problems" that would eventually have caused its collapse even without its defense and imperial expenditures. (However, the speed with which it had to slash those expenditures after the end of the Cold War is clear proof of just how burdensome military expenditures can be.)

  Economic causation is indeed slippery - but it is not that slippery that it can be twisted to support these Mearsheimer contentions. The denial of the inherent financial burdens of military spending is a key fallacy in his theory - and is clearly inconsistent with his acknowledgement that the financial costs of conflict can greatly weaken combatants.
  &
  Apparently, Mearsheimer has accepted the Keynesian stupidity about the equivalence of the "government sector" and the "private sector" in determining economic strength. Those failed disastrous 20th century experiments in socialist and command economic systems, and the failures of Keynesian policies in the 1970s, teach him nothing. Only by such sloppy historic analysis as Mearsheimer provides in this segment can heavy military expenditures be viewed as anything but a grave economic burden - and a substantial limitation to the long term ability to increase and sustain military power.

  This does not mean that war and military spending are futile, as some pacifists prefer to believe. Mearsheimer properly points out many of the obvious advantages of victory. As Gen. MacArthur pointed out, there is no substitute in war for victory. Even if most developed nations today cannot act with the requisite ruthlessness to make an occupation pay as a long term proposition, that does not mean that there are no potential or real adversaries in today's world prepared to use any levels of ruthlessness required for their ends.
  &

Great power strategies:

"Great powers that care about their survival should neither appease nor bandwagon with their adversaries." Joining a bandwagon is the strategy of weaker powers.

 Strategies used in international power politics include:

• Blackmail: This is gunboat diplomacy - effective mainly against weaker nations - and is seldom successful against great powers. The Munich settlement is a notorious exception.
• Bait and bleed: By causing a war between two rivals - or by lengthening such a conflict by assisting the weaker combatant - both can be weakened by protracted conflict. This tactic is seldom successful. (The Iran-Iraq war provides a recent example - overlooked by Mearsheimer, perhaps because the combatants were not major powers.)
• Bloodletting: By aiding the opponent of a rival great power, a conflict can become protracted and costly. The U.S.-Vietnam conflict, and the Soviet-Afghanistan conflict, are two examples.
• Balance of power: Great powers combine in alliances or support groups to deter rising states that may seek hegemonic status. This worked during the Cold War as the U.S. successfully contained the Soviet Union in Europe. However, this strategy failed in 1914 - leading to WW-I. (The restraining impact of nuclear weapons may have been the key difference.)
• Buck passing: Great powers prefer to let other great powers assume the burdens of balancing against rising states. An obviously unsuccessful example was the Soviet Union leaving Britain and France alone to face Nazi Germany early in WW-II.
• Appeasement, and joining a bandwagon: For great powers, these strategies are inherently flawed, since they concede predominant power to an aggressor. "Great powers that care about their survival should neither appease nor bandwagon with their adversaries." Joining a bandwagon is the strategy of weaker powers.
• Imitation and novelty: States both imitate the successful practices of other states, and seek novel strategies and weaponry that may provide advantages.

  Prussian expansion in the 19th century was not opposed because, according to Mearsheimer, all the existing European great powers viewed the strengthened Prussia as a counterweight against existing adversaries. For two decades, the new Germany did indeed separate the old rivals.
  &
  U.S. efforts to stay out of the WW-I  and WW-II were the most successful unsuccessful efforts at buck passing. Even though eventually dragged into those conflicts, the delay allowed the U.S. to profit enormously during the periods of neutrality, and materially reduced its ultimate costs in men and material. Its relative financial strength was vastly enhanced by both conflicts.
  &
  U.S. restraint in gaining further territory in North America during the 20th century is lightly dismissed with the contention that the U.S. didn't need any more territory.

  This is hardly convincing. Canada, at least, is a resource rich, thinly populated plum - but was left unmolested during the 20th century.
  &
  Hegemony is not empire. States that concede hegemonic power to more powerful states do not thereby doom their survival - as long as the hegemonic state does not seek empire. Today, Mexico and Canada live in peace and security next to the U.S. colossus. 

  The "second front" delay during WW-II is viewed as "inadvertent buck passing" at Russia's expense.

 Not only is this an oxymoron, it is a repetition of a clearly untenable left wing propaganda myth that has long since been discredited. Until 1944, the U.S. and U.K. clearly were incapable of a second front in France. Their efforts in the Mediterranean and in the air and sea war and by posing threats all around Europe in fact diverted major German units and resources from the Eastern front. These activities in fact constituted the most effective "second front" that they were capable of before 1944. The U.S. also literally kept Japan off Russia's back during Russia's period of maximum vulnerability in 1941 and 1942.

The offshore balancers:

  Japan, on the other hand, acted as a potential hegemonic state rather than as just an offshore balancer, but this was solely because of the weakness of the continental states of Asia at that time.

  Mearsheimer's theory is self-confirming to  some extent. In the absence of an aggressive great power, there is no potential hegemonic state because no state has taken the trouble to build a huge expensive army. Such was the state of affairs after the Napoleonic Wars. This system is naturally "balanced" and less warlike - practically by definition - even if one state could, if it wanted to, quickly build dominant military strength.
  &
  It is only when a potentially dominant state comes under aggressive leadership and builds superior military strength that a multipolar world becomes unbalanced and dangerous -- but that may be as much because of the aggressive regime as because it is a multipolar world with a potentially dominant great power.

Implications for the 21st century:

"Realism will offer the most powerful explanations of international politics over the next century, and this will be true even if the debates among academic and policy elites are dominated by non-realist theories. In short, the world remains a realist world."

Instability in Europe and Northeast Asia is destined to grow, as the great powers realize their power potential. Clearly, "a rising China is the most dangerous potential threat to the United States in the early twenty-first century."

  Given the continued anarchic structure of the international political system, the security needs of great powers will continue to drive them in the same way as before.

  "In fact, all of the major states around the globe still care deeply about the balance of power and are destined to compete for power among themselves for the foreseeable future. Consequently, realism will offer the most powerful explanations of international politics over the next century, and this will be true even if the debates among academic and policy elites are dominated by non-realist theories. In short, the world remains a realist world."

  That the U.S. has to keep 100,000 men in both Europe and Northeast Asia to keep the peace is proof that nothing has changed. Russia, Germany, China and Japan all have the potential to rise to great power status and play great power strategic roles.
  &
  Within the next two decades, Mearsheimer thus predicts, instability in these two vital regions is destined to grow as these nations realize their power potential. Clearly, "a rising China is the most dangerous potential threat to the United States in the early twenty-first century."
  &
   Mearsheimer sets forth some theoretical assumptions upon which this prediction is based.

1. "States are the key actors in world politics, and they operate in an anarchic system;
2. great powers invariably have some offensive military capability;
3. states can never be certain whether other states have hostile intentions;
4. great powers place a high premium on survival; and,
5. states are rational actors who are reasonably effective at designing strategies that maximize their chances of survival."

  Currently, this is obviously wrong with respect to great power conflict. Today, no state except the United States can project enough power to threaten even a neighboring great power - and the U.S. could launch a conventional attack against a great power only with great difficulty and an extensive military buildup. Moreover, the U.S. could not sustain an unwelcome occupation, so it would gain nothing from such an effort. Even the possible burdens of an occupation of Iraq cause hesitation.
  &
  Also, no democratic party in power would welcome the diversion of resources from domestic spending that would be needed to reach such levels of military power. Indeed, even Russia finds military expenditures an unwelcome burden.

Even under the terms of offensive realism, there are currently no threats to the survival of China. Just by being China, China achieves hegemonic status on the mainland of Asia.

  Only China, today, shows definite inclinations at building military strength beyond levels reasonably needed for defense. Mearsheimer correctly notes that China was seriously assaulted in the past, but modern China is clearly not threatened by anyone. Here, the driving force is clearly ambition.
  &
  China is certainly not driven by fear of an attack by the U.S. across the Pacific Ocean. By the terms of offensive realism, the U.S. - as an offshore balancer - is not a threat to China.
  &
  Even a remilitarized Japan - something that could not  occur without an expensive and time consuming buildup - could not threaten modern China. Japan - as another offshore balancer - is no threat to a China that has achieved great power status. Moreover, the Chinese military buildup is the surest way of ultimately generating a remilitarized Japan.
  &
  Thus, even under the terms of offensive realism, there are currently no threats to the survival of China.
  &
  Also, just by being China, China achieves hegemonic status on the mainland of Asia. Within its own borders, it controls 20% of the world. Only ambitions to take control of Taiwan and to take advantage of perceived weaknesses across its borders drives Chinese military expansion.
  &
  Mearsheimer notes that China has many unresolved border disputes, but none of these threaten its survival. The most serious flash point remains Taiwan, however, and Taiwan is certainly no threat to China.

It is still only the presence of U.S. troops that allows the rest of Europe to feel comfortable with a unified Germany - and Germany itself benefits greatly from the lack of great power concern over its superior strength. It is only the presence of U.S. forces in Northeast and Southeast Asia that gives Japan and the smaller nations of those regions confidence that peace can be maintained in those regions.

    The most likely realist scenario is that great power rivalry will flare into limited warfare conflicts at the periphery of great power interests. There will be conflicts over interests in client states - rather than direct attacks on each other. If Russia were not so weak, it might have more strongly supported its Serb allies. China still backs North Korea, while the U.S. still supports South Korea. France and England still have widespread special interests outside their great power relationships, and Germany is building special interests in Central Europe.

  However, only on the Korean Peninsula and across the Taiwan Straits do these interests pose a threat to the balance of power or the security of great powers.

  It is still only the presence of U.S. troops that allows the rest of Europe to feel comfortable with a unified Germany - and Germany itself benefits greatly from the lack of great power concern over its superior strength. It is only the presence of U.S. forces in Northeast and Southeast Asia that gives Japan and the smaller nations of those regions confidence that peace can be maintained in those regions.
  &
  "Conquest" can still, today, achieve "significant economic benefits." Competition over sparsely populated or weakly held resource rich regions - like Siberia or the South China Sea - will still tempt Chinese leaders concerned with the enhancement of Chinese power.
  &

The United States will leave Europe or Northeast Asia because it does not have to contain an emerging peer competitor, in which case the regions would become less stable, or the United States will stay engaged to contain a formidable rival in what is likely to be a dangerous situation.

  Japan is currently not a great power as that is defined under offensive realism. China, Russia and the U.S. are the relevant great powers in Asia. The strongest - the U.S. - is an "offshore balancer" - and nuclear arsenals also are a factor for caution and peace. Neither China nor Russia can currently project much power. Thus, peace prevails - at least at present.
  &
  The evident lack of U.S. interest in extending its hegemonic power into Europe or Asia explains why no coalitions form against it. It avoids the fear and loathing directed at aggressive great powers that have the potential to achieve hegemonic status.
  &
  However, the current peaceful balances are unlikely to continue. Offensive realism predicts:

  "In short, either the United States will leave Europe or Northeast Asia because it does not have to contain an emerging peer competitor, in which case the region would become less stable, or the United States will stay engaged to contain a formidable rival in what is likely to be a dangerous situation. Either way, relations between the great powers are likely to become less peaceful than they were during the 1990s."
  &
  It is hard for this prediction to be totally wrong, since great power relations were almost totally peaceful in the 1990s. If there is substantial great power military rivalry, threats and/or conflict by 2020, the question will remain as to whether it was ambition or fear for survival that was most responsible.

Europe:

The removal of the U.S. presence would mean that all the European great powers would have to look to their own defenses, and rebuild their military strength - including nuclear arsenals where those do not currently exist.

  Of course, the removal of the U.S. presence would mean that all the European great powers would have to look to their own defenses, and rebuild their military strength - including nuclear arsenals where those do not currently exist.

  In fact, the U.S. - and Germany, too - have long recognized the need for a substantial U.S. presence in Europe to permit the other European nations to live in comfort with Germany. The U.S. interest in a peaceful, prosperous Europe remains not just strong, but paramount - since nothing threatens U.S. interests as much as instability in Europe.
  &
  In fact, the U.S. has long encouraged improvements in European military capacity - but the expense of such improvements has not been willingly accepted by Europe's political leaders - and Europe's military capabilities thus remain puny. Even without the reemergence of Russia as a threat, NATO is likely to remain a fixture of the European scene.

Northeast Asia:

  However, if China continues its impressive efforts at economic reform, and continues rapid economic growth, it becomes a potential hegemonic power that is far too strong to be contained without U.S. intervention.

  "Engagement policies and the like would not dull China's appetite for power, which would be considerable."

  Thus, the U.S. policy of engagement with China and encouragement of its incorporation into the international community to facilitate its economic growth and prosperity are viewed as misguided. "The United States has a profound interest in seeing Chinese economic growth slow considerably in the years ahead." Otherwise, China will soon become powerful enough to consider adopting its own Monroe Doctrine. It will attempt to push the U.S. out of Northeast Asia, and become the second regional hegemonic power in the world and a serious threat to the U.S.
  &
  If the U.S. persists in liberal policies that "contradict balance of power logic" - if it continues to "turn its back on the realist principles that have served it well since its founding" - this will prove to be "a grave mistake." 

Whether attributed to ambition or security fears - Mearsheimer is clearly correct in identifying Chinese muscle flexing as the greatest threat to peace between the great powers during the next two decades.

  It is indeed hard to imagine an economically powerful China whose leaders would not at some time succumb to ambitions. Even if the Taiwan problem could be peacefully resolved - perhaps as a semi-autonomous province of an eventually democratic China - China still has claims in the South China Sea - opportunities to dominate small states along its Central Asian borders - and if Russia fails to get its act together, a tempting resource rich, sparsely populated Siberia beckons across its northern border.
  &
  However, the U.S. really has little power to influence China's economic development either positively or negatively. China's economic development depends entirely on China's success in becoming a capitalist nation. However, in that case, it may indeed become so dominant in Asia that incremental expansion along its borders may become too insignificant to bother with - just as the U.S. decided against further expansion at the expense of Canada and/or Mexico in North America.
  &
  After all, domination by means of capitalist investment can be far more practical than military conflict and occupation. After all, capitalist states always have the alternative - the generally preferable alternative - of relying on economic power rather than military power to enhance their national power and security. The U.S. may indeed have frequently sent the marines into Latin American nations, but almost all of those military efforts were temporary. Its economic interests are permanent.
  &
  And Mearsheimer - and Keynes - to the contrary notwithstanding, military expenditures are ALWAYS a burden on economic development.
  &
  Offensive realism, of course, generally ignores the extent to which ambition - rather than just security fears - drive the leadership decisions of aggressive great power states. Clearly, this distinction is not overly subtle and cannot be dismissed as unimportant. However - whether attributed to ambition or security fears - Mearsheimer is clearly correct in identifying Chinese muscle flexing as the greatest threat to peace between the great powers during the next two decades.
  &
  Nevertheless, today's great powers have many strong mutual interests. Indeed, the common threat of irregular "terrorist" conflict has - to a remarkable degree - driven all the great powers to recognize the predominance of common interests over their still very real conflicting interests.
  &
  As a growing commercial power, China will have mutual interests in an orderly, predictable commercial world. China, to a similar but lesser extent than the European great powers, has an interest in avoiding the burdens of the arms race that it might provoke with Japan and Russia. A continued U.S. presence in the region provides the best chance of avoiding such an arms race and assuring stability and peace.