AP Photo

Why has it been nearly impossible to coax Taliban fighters into turning in their weapons and cooperating with the Afghan government? The story of Mullah A stands as an all-too-common example.

A few years back, the Taliban commander thought his personal war with the Americans was over when he surrendered his Toyota Land Cruiser, a stack of rocket-propelled grenades and his personal weapons to the police chief in Kandahar. Mullah A, who prefers not to be identified, was exhausted. In late 2001, when U.S.-backed forces were pushing into northern Afghanistan, the commander saw most of his men wiped out by heavy American bombardment. He was one of the few survivors, and he fled south, back home to Kandahar, convinced that his fighting days had come to an end.

As part of the...