WASHINGTON — The deadly rescue mission in Afghanistan in 2002 began when Petty Officer First Class Neil C. Roberts, a member of the Navy’s classified SEAL Team Six, fell out of a helicopter that came under enemy fire as it tried to land on the snowy ridge line of an 11,000-foot mountain.

Petty Officer Roberts was swarmed by Qaeda fighters almost immediately, and was nearly certain to die, but teams of Special Operations troops and Army Rangers were sent to the mountain in an attempt to rescue him. By nightfall, seven American troops had died on the jagged rocks that came to be known as “Roberts Ridge.” Petty Officer Roberts’s body was eventually found and taken off the mountain.

That costly attempted rescue remains one of the most vivid examples of the military’s time-honored ethos to leave behind none of its own on the battlefield. It is a tradition that has underpinned American efforts to rescue service members captured or stranded behind enemy lines from World War II to Vietnam to the “Black Hawk Down” raid in Somalia and the war in Afghanistan.

But now this credo is being questioned by critics who say it is one thing to risk lives to rescue a comrade captured in battle, and another to take the same risks for someone they accuse of being a deserter.