You can fault some of the particulars of Obama’s policy. I’m scratching my head about the logic of his timetable for reversing the surge he announced 18 months ago: Pulling out 10,000 troops this year is okay, but why yank out an additional 23,000 in the middle of next year’s fighting season? That encourages a battered Taliban to hang on awhile longer rather than bargain for a truce. It repeats the tip-your-hand mistake I thought Obama made back in December 2009, when he set a date for beginning the withdrawal of his surge forces even as he ordered them into battle.

But on the larger theme, I thought Obama had it right. This period of expeditionary wars does need to come to an end — not just because America is weary and broke but because the dialectic of history has brought the world to a new place. If American military might has been shown to have limited effect in shaping events over the past 10 years, so have the terrorist strategies of al-Qaeda and the Taliban…

Obama concluded that this counterterrorism side of counterinsurgency works far more reliably than the uncertain, nation-building side. The embrace of counterterrorism tactics makes sense as an exit strategy from Afghanistan, and as a continuing check against al-Qaeda. But America should understand that this is a dark face of war — something perilously close to combat by assassination. It needs more debate before it’s elevated to a cornerstone of American strategy.