Almost daily we read of America’s “waning power” and “inevitable decline,” as observers argue over the consequences of defense cuts and budget crises.

Yet much of the new American “leading from behind” strategy is more a matter of choice than of necessity. Apparently, both left-wing critics of U.S. foreign policy and right-wing Jacksonians are tiring of spending blood and treasure on seemingly ungrateful Middle Easterners — after two Gulf wars, the decade in Afghanistan, and various interventions in Lebanon and Libya....