U.S. Defense Secretary Robert Gates fired the top U.S. general in Afghanistan on May 11, replacing him with a former special forces commander in a quest for a more agile, unconventional approach in a war that has gone quickly downhill.

Gen. David McKiernan AP PHOTO

With the Taliban resurgent, the switch from Gen. David McKiernan to Lt. Gen. Stanley McChrystal suggests U.S. President Barack Obama wants major changes in addition to the additional troops he's ordering into Afghanistan to shore up the war effort.

McKiernan, on the job for less than a year, had repeatedly pressed for more forces. Although Obama has approved more than 21,000 additional troops this year, he has warned that the war will not be won by military means alone.

Gates echoed that view at a grim Pentagon news conference announcing the leadership overhaul. "As I have said many times before, very few of these problems can be solved by military means alone," he said. "And yet, from the military perspective, we can and must do better."

A new team of commanders will be charged with applying Obama's revamped strategy for challenging an increasingly brutal and resourceful insurgency. The strategy, still a work in progress, relies on the kind of special forces and counterinsurgency tactics McChrystal knows well, as well as non-military approaches to confronting the Taliban.

Gates said he asked for McKiernan's resignation "with the approval of the president."

The White House said the recommended change came from the Pentagon.