The crucial role played by American warplanes in Afghanistan also raises questions about the prospects for the fight against the Taliban in the future.
It was an evening in October last year, and Mr. Qayum was meeting several Afghans in a field. Though he did not know it, a Navy F/A-18 strike fighter was circling high overhead more than five miles away, summoned by an American Special Operations team. Its engines were out of earshot, the pilot said, "so we didn't burn the target."
Mr. Qayum led a platoon-size Taliban group and was plotting to bomb an Afghan government office, an American intelligence officer said. Under Western rules guiding the use of deadly force, the pilot was barred from trying to kill him while he stood in a group of unidentified men.
Then came a chance. The meeting ended, and Mr. Qayum approached a man who had pulled up on a motorcycle, the pilot and the intelligence officer said. Soon the two men were riding together on a dirt road, illuminated on the screen of the aircraft's targeting sensor.
The pilot, Lt. Cmdr. Brian Kesselring, released an AGM-65E laser-guided missile. Visible on a video recording declassified and released to The New York Times, the missile struck the pair head-on, exploding with such energy that only fragments of Mr. Qayum's remains were found.