WASHINGTON: President Barack Obama fired the top U.S. general in Afghanistan on Monday, 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. With the Taliban resurgent, Obama's switch from Gen. David McKiernan to Lt. Gen. Stanley McChrystal suggests the new commander in chief 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, has 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.

Defense Secretary Robert 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."

"It's time for new leadership and fresh eyes."

A new team of commanders will now 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 nonmilitary approaches to confronting the Taliban. It would hinge success in the seven-year-old war to political and other conditions across the border in Pakistan.

McKiernan, named to his post by former President George W. Bush, had expected to serve into next year but was told he was out during Gates' visit to Afghanistan last week.

Gates said he asked for McKiernan's resignation "with the approval of the president." The chairman of the Joint Chiefs of Staff, Adm. Mike Mullen, and McKiernan's military boss, Gen. David Petraeus, both said they supported the switch.

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

"The president agreed with the recommendation of the secretary of defense and chairman of the Joint Chiefs of Staff that the implementation of a new strategy in Afghanistan called for new military leadership," White House spokesman Robert Gibbs said in a statement.

McChrystal is a former special forces chief credited with nabbing one of the most-wanted fugitives in Iraq. Taking a newly created No. 2 slot under his command will be Lt. Gen. David Rodriguez, a veteran of the Afghanistan fight who has been Gates' military shadow, the top uniformed aide who travels with him everywhere.

By year's end, the United States will have more than 68,000 troops in the sprawling country — about double the total at the end of Bush's presidency but still far fewer than the 130,000 still in Iraq.

McKiernan and other U.S. commanders have said resources they need in Afghanistan are tied up in Iraq.

Although Obama had pledged to add forces in Afghanistan while shutting down the Iraq war, his new administration has sought firmer control over the pace and scope of any new deployments. Gates and Mullen have both warned Obama that a very large influx of U.S. troops would be self-defeating.

Asked if McKiernan's resignation would end his military career, Gates said, "Probably." But he praised the general's long service, and when pressed to name anything McKiernan had failed to do, Gates demurred.

"Nothing went wrong, and there was nothing specific," he said.

Gates, too, was appointed to his position by former President George W. Bush. He noted that the Afghan campaign has long lacked people and money in favor of the Bush administration's focus since 2003 on the Iraq war.

"But I believe, resources or no, that our mission there requires new thinking and new approaches from our military leaders," he said. "Today we have a new policy set by our new president. We have a new strategy, a new mission and a new ambassador. I believe that new military leadership also is needed."

McKiernan issued a short statement in Kabul.

"All of us, in any future capacity, must remain committed to the great people of Afghanistan," McKiernan said. "They deserve security, government that meets their expectations, and a better future than the last 30 years of conflict have witnessed."

In June 2006 Bush congratulated McChrystal for his role in the operation that killed Abu Musab al-Zarqawi, the leader of al-Qaida in Iraq. As head of the special operations command, McChrystal's forces included the Army's clandestine counterterrorism unit, Delta Force.

He drew criticism for his role in the military's handling of the friendly fire shooting of Army Ranger Pat Tillman — a former NFL star — in Afghanistan. An investigation at the time found that McChrystal was "accountable for the inaccurate and misleading assertions" contained in papers recommending that Tillman get a Silver Star award.

McChrystal acknowledged he had suspected several days before approving the Silver Star citation that Tillman might have died by fratricide, rather than enemy fire. He sent a memo to military leaders warning them of that, even as they were approving Tillman's Silver Star. Still, he told investigators he believed Tillman deserved the award.