Mandelbaum’s latest book offers a biting sketch of U.S. foreign policy during the Clinton, George W. Bush, and Obama administrations, skewering all three for their various mistakes. He argues that, bequeathed a rare gift of peace, prosperity, and relative international calm, the post–Cold War presidencies often wandered off into undisciplined adventures in humanitarianism and quixotic nation building, most of which turned out badly. Instead of squandering blood, treasure, and reputation on “foreign policy as social work” (as Mandelbaum put it in these pages two decades ago), Washington should have focused on other countries’ external behavior, not their internal politics. Mandelbaum’s blows hit their targets, as does his theoretical contention that the most important factor driving these policies was unprecedented relative power—the strong doing what they can once again, this time in a well-intentioned but clueless American mode. But since the author favors continuing “the American role as the chief custodian of the benign international order that . . . emerged from the end of the Cold War,” it is not clear why the new era is truly distinctive, and the book would have benefited from less narration of familiar events and more discussion of the author’s preferred courses of action.