Then we should have pulled out of Afghanistan in the late fall of 2001, after Kabul had fallen. We had punished Al-Qaeda’s hosts; what need to stay on?

We go not abroad in search of monsters to destroy, as JQA said. But when the monsters have come to destroy us we must be proactive. Proactivity in the modern world means more than keeping the “barbarians” on the hop, as imperial China would have said. The policy didn’t always work for imperial China.