INSIDE STRIKE FIGHTER VENGEANCE 13, over Kandahar Province, Afghanistan — Cmdr. Layne McDowell glanced over his left shoulder, through the canopy of a Navy F/A-18, to an Afghan canyon 9,000 feet below. An American infantry company was down there.

The soldiers had been inserted by helicopter. Now a ground controller wanted the three strike fighters circling overhead to send a sign — both to the grunts and to any Taliban fighters shadowing them as they walked.

Commander McDowell banked and aligned his jet’s nose with the canyon’s northeastern end. Then he followed his wingmen’s lead. He dived, pulled level at 5,000 feet and accelerated down the canyon’s axis at 620 miles per hour, broadcasting his proximity with an extended engine roar.

In the lexicon of close air support, his maneuver was a “show of presence” — a mid-altitude, nonlethal display intended to reassure ground troops and signal to the Taliban that the soldiers were not alone. It reflected a sharp shift in the application of American air power, de-emphasizing overpowering violence in favor of sorties that often end without munitions being dropped.