Christopher Preble has a solid critical review of Robert Kagan’s new book at The National Interest. Preble is particularly concerned with the free-rider problem:

EVEN THOSE inclined to believe Kagan’s assessment of the international system and America’s role in it must contend with one central fact that Kagan elides: the costs of maintaining the status quo are substantial and likely to grow. That is because Washington’s possession of vast stores of power—and its willingness to use that power on behalf of others—has created an entire class of nations that are unwilling to defend themselves and their interests from threats. The data clearly show a vast and growing gap between what others pay for defense and what Americans pay to defend them. The critical question, then, centers on differing perceptions of this capability imbalance. Because U.S. security guarantees to wealthy allies have caused them to underprovide for their own defense, they also have less capacity to help the United States in its time of need—either now in Afghanistan or in a theoretical future contest with China or a resurgent Russia. Kagan contends other countries will choose not to defend themselves and their interests, but at other times he acknowledges it is precisely the presence of American power that has discouraged them from doing so. In the end, it is clear Kagan doesn’t want other countries to defend themselves because, he says, they just can’t be trusted to get the job done. Most will be content to let security challenges grow and fester on their borders, or within them, leaving the United States—and the United States alone—with the task of cleaning up the mess. As he sought to explain in 2003, Americans should “be more worried about a conflagration on the Asian subcontinent or in the Middle East or in Russia than the Europeans, who live so much closer,” because the harm from other countries’ failure to act will inevitably threaten U.S. security.

This is spot on: from a pro-primacy position, depressing non-US defense spending via security guarantees is a feature, not a bug. The positive case is that it reduces the risks of interstate war and otherwise suppresses rivalries. From a US perspective, it also enhances Washington’s influence. The negative case is, as Preble stresses, that it shifts the burden of others’ security onto the US taxpayer and may hasten relative decline.

As recent Japanese-ROK security agreements suggest, this doesn’t amount to an all-or-nothing deal. States in the US umbrella that feel sufficiently worried about their security won’t ignore their own needs. In this context, the Asia pivot also makes sense, as the major European powers really aren’t that concerned about traditional military threats. I see no problem with rejecting Kagan’s Manichaeanism, recognizing that the US does have significant room for defense savings, but still acknowledging the central place of the US in many aspects of global security–and acting accordingly.