Has the hour of offshore balancing struck? Sometimes you get that sense. U.S. defense budgets are on the wane, and with them the wherewithal to undertake ambitious foreign ventures. Sentiment does seem to be coalescing behind the idea that the United States should draw down expensive Eurasian entanglements, many of which provide little obvious return on the investment. If Washington cuts its commitments, it can cut down on the resources it uses to uphold those commitments. Ends will remain aligned with reduced ways and means. And to be sure, the logic of offshore balancing is seductive. If America no longer carries as big a stick as it once did, it must make doubly sure to speak softly — avoiding overextending itself and stoking needless antagonisms.

A central assumption for proponents of a more offshore posture is that the international system is mainly self-regulating. If China becomes a domineering great power, that is, lesser neighbors will make common cause. They will augment and aggregate their diplomatic, economic, and military might, constituting an ample counterweight. Only in extreme — and highly improbable — circumstances will they need outsiders to step in to tip the military balance against a would-be hegemon. Some offshore balancers just want to quit the Eurasian continent, retiring to (relatively) nearby bases like Japan and Guam. Purists clamor to bring the boys home and balance from North America. Not only can the United States pull back from the Eurasian rimlands, in their view; it can do without undue risk. The weary titan can set down his load at last.

Great-power balancing lies at the core of the realist school of international relations. There’s doubtless considerable truth to it. The inexorable logic of self-help — and self-preservation — impels societies to join against overbearing antagonists. As Benjamin Franklin quipped before signing the Declaration of Independence, you can hang together or hang separately. But does the logic of balancing warrant the confidence offshore balancers vest in it? Not necessarily. International-relations theory derives in large part from studying 19th-century Europe, where coalitions among roughly comparable great powers indeed offset one another until the rise of a far greater power in Europe's midst, Imperial Germany, upset the system. The United States ultimately had to add its weight to the European balance — twice. So much for a self-administering European Concert.

How about the Western Hemisphere? Who balanced against the United States during its ascent to regional primacy? No one, really. Unable to outmatch the U.S. Navy in its own backyard, and with a naval arms race to run in the North Sea, Great Britain and its Royal Navy beat a quiet retreat from the Americas toward the end of the 19th century. That left Latin America — chiefly the powers ringing the Caribbean Sea, where most U.S. interests resided. Governments there showed little sign of balancing behavior. They showed no sign of effective balancing — even during the banana wars, when Washington repeatedly landed troops in Caribbean nations for reasons good and ill.

Neither the European nor the American experience, then, lends much credence to the notion that regional balances are self-enforcing. Will the Far East prove different? Maybe. But neither history nor the lopsided distribution of power among Asian nations justifies assuming the region can shift for itself. Whether offshore balancing represents a feasible U.S. strategy will depend on whether China's neighbors look to their defenses effectively, and on how well they coordinate policy and strategy. Baby steps in that direction on the part of Japan, Australia, and India provide some cause for hope. But as we all know, hope is not a strategy.