Interview with the Author

Foreign Affairs: Your article is about the likelihood of great-power competition in Europe and Northeast Asia over the next 10 years or so. Should the United States withdraw the forces it has maintained in those regions for more than fifty years, especially since you argue that they have had a pacifying effect in each region? Also, you argue that Europe is bipolar now with Russia and the United States as the reigning great powers, but that if the United States withdraws Europe is likely to become multipolar with Britain, France, Germany, Italy, and Russia as the great powers. Indeed, you argue that Germany would be a "potential hegemon" in a multipolar Europe. Is multipolarity always unstable? And what characterizes a "potential hegemon"?

John J. Mearsheimer: I argue that U.S. troops will and should remain in Europe and Northeast Asia only if there is a potential hegemon in those regions that the local great powers cannot contain by themselves. I do not believe that the United States will maintain a military presence in those regions 1) if there is a potential hegemon that can be contained by other states, or 2) for the purpose of keeping peace among the great powers. There are a number of reasons why the present alliance structures in Europe and Northeast Asia are likely to fall apart over time. But the main reason is costs-both the financial costs to the United States of maintaining huge military establishments in those regions and, more importantly, the potential human costs that come with putting American men and women in harm's way.

Like virtually all other peoples, Americans are only willing to fight and die when vital interests are at stake. Although it is certainly in America's national interest to contain a potential peer competitor, it will prefer that other states assume that burden, if it is possible to pass the buck to them. To put it bluntly, why should the United States defend countries that are capable of defending themselves? While preserving peace in Europe and Northeast Asia might be in America's interest, that goal is not important enough to justify the loss of American lives, as the United States demonstrated clearly in NATO's 1999 war against Yugoslavia.

Regarding multipolarity, it is not always unstable. If one compares multipolar Europe between 1900 and 1945 with bipolar Europe between 1945 and 1990, it might seem that multipolar systems are especially prone to deadly wars. However, Europe was also multipolar from 1815 to 1853, as well as 1871 to 1914, and there were no wars between the European great powers during those two lengthy periods. Thus, some multipolar systems are more stable than others. The key determinant of stability in multipolarity is whether or not the system contains a potential hegemon. If one state thas the wherewithal to dominate all of its rivals-like Napoleonic France, Wilhelmine Germany, orNazi Germany-multipolarity is likely to be especially dangerous. In the absence of a potential hegemon, war among the great powers is still possible, but not nearly as likely.

A potential hegemon is more than just the most powerful state in the system. It is a great power with so much actual military capability and so much potential power that it stands a good chance of subduing and controlling all of the other great powers in its region of the world. A potential hegemon need not have the wherewithal to fight all of its rivals at once, but it must have excellent prospects of defeating each opponent alone, and good prospects of defeating some of them in tandem. The key relationship, however, is the power gap between the potential hegemon and the second most powerful state in the system: there must be a marked gap between them. To qualify as a potential hegemon, a state must have-by some reasonably large margin-the most formidable army as well as the most latent power among all the states located in its region.

FA: U.S.-China relations have been turbulent since President Bush took office, leaving many Americans confused about what Beijing's intentions are and what Washington's approach should be. You criticize the policy of "constructive engagement" with China that prevailed in the last decade. In your view, although China is not yet a potential hegemon in Northeast Asia, it is a rising power that could become a superpower capable of rivaling the United States. U.S. policy should therefore be directed toward thwarting China's rise. Do you have a sense of what tack the Bush administration will take? Is there a particular issue-i.e. Taiwan, human rights, China's relations with Russia-that could tip the balance?

Mearsheimer: It is important to emphasize that China still has a long way to go before it can be a potential hegemon that needs to be contained. The key to its future is what happens to its economy. I believe that the United States has a deep-seated interest in making sure that China does not become a wealthy country, because it will translate its economic might into military might and seek to dominate Asia. The United States and its allies in Asia would have their hands full trying to contain China, because a wealthy China would be a particularly formidable foe. Better to head that problem off at the pass by doing everything possible to slow down China's modernization.