KABUL, Afghanistan — American and NATO troops firing from passing convoys and military checkpoints have killed 30 Afghans and wounded 80 others since last summer, but in no instance did the victims prove to be a danger to troops, according to military officials in Kabul.

“We have shot an amazing number of people, but to my knowledge, none has ever proven to be a threat,” said Gen. Stanley A. McChrystal, who became the senior American and NATO commander in Afghanistan last year. His comments came during a recent videoconference to answer questions from troops in the field about civilian casualties.

Though fewer in number than deaths from airstrikes and Special Forces operations, such shootings have not dropped off, despite new rules from General McChrystal seeking to reduce the killing of innocents. The persistence of deadly convoy and checkpoint shootings has led to growing resentment among Afghans fearful of Western troops and angry at what they see as the impunity with which the troops operate — a friction that has turned villages firmly against the occupation.

Failure to reduce checkpoint and convoy shootings, known in the military as “escalation of force” episodes, has emerged as a major frustration for military commanders who believe that civilian casualties deeply undermine the American and NATO campaign in Afghanistan.