Defense Secretary Robert Gates abruptly removed the top US commander from Afghanistan Monday, replacing him with a general whose background in special operations may signal a desire to further refine the military strategy there.

Gates's nominee, Lt. Gen. Stanley McChrystal, led Joint Special Operations Command until last year, and "his focus and his background are very relevant to our needs there," Secretary Gates said at a Pentagon press conference Monday. Some analysts believe the mission in Afghanistan needs a greater focus on special operations, because such missions involve relatively few troops but can have a large impact.

General McChrystal, for example, is credited with overseeing the attack that killed Abu Musab al-Zarqawi, the head of Al Qaeda in Iraq, in 2006. If confirmed by the Senate, he will replace Gen. David McKiernan, who has been criticized in some quarters for lacking new ideas on how to implement President Obama's strategy for Afghanistan.

Gates said McChrystal will bring "fresh eyes" to the worsening security situation in Afghanistan, where attacks are up 73 percent compared with last year, according to NATO.

"That's the challenge that we give to the new leadership," said Gates. "How do we do better? What new ideas do you have? What fresh thinking do you have? Are there different ways of accomplishing our goals?"

The firing harked back to 2006, when President Bush replaced the top commander in Iraq, Gen. George Casey, with Gen. David Petraeus about the same time he "surged" troops there under a new strategy. Likewise, Mr. Obama announced a new strategy for Afghanistan this spring, committing more than 21,000 additional troops to the country and sending a new ambassador two weeks ago.

On Monday, Gates also nominated his own chief of staff, Lt. Gen. David Rodriguez, to a newly created position in Kabul that will oversee day-to-day operations. This is expected to result in greater US control over the multinational mission there.

Both McChrystal and General Rodriguez have recent experience in Afghanistan.

McChrystal, who now heads the Joint Staff at the Pentagon under Adm. Mike Mullen, has mostly stayed behind the scenes, given his background in special operations. But he has recently led an effort to have certain units redeploy to the same places in Afghanistan again and again in order to build longer-term relationships with the population. The plan is still in the development stage.

Before Rodriguez became Gates's chief of staff last year, he was thecommander of the 82nd Airborne Division in the eastern region ofAfghanistan, where the US-led counterinsurgency effort is seen ashaving some success. Gates stressed that Rodriguez's knowledge ofAfghanistan is essential. [Editor's note: The original version misstated Rodriguez's command in eastern Afghanistan.]

Gates has earned a reputation for firing top Pentagon officials for poor performance, but he offered no details about why he asked General McKiernan to resign. McKiernan did "nothing wrong and there was nothing specific," Gates said.

McKiernan had long been vocal about the need for more troops – and was about to receive much of what he had asked for. But he had asked for an additional 10,000 troops on top of what Obama is already sending – a request Gates has said he would be loath to approve. But Gates said Monday that the difference of opinion on troop strength had nothing to do with his decision.

Administration officials may have been looking for a way to animate Obama's new strategy with new leadership, some experts say. While Gates credited McKiernan with reducing civilian casualties – a key factor in an effective counterinsurgency – McKiernan's low-key leadership style drew some criticism.

"It's an important break from the Bush administration," says one Senate staffer, who could speak to the press only on the condition that his name not be used. "It's actually a very encouraging sign."

There has been concern in Washington that McKiernan had yet to figure out a way to implement the new strategy Obama released this spring. The apparent lack of what's known as a "joint campaign plan" – a document that would detail the way in which American forces would operate under the new strategy – gave rise to fears in some quarters that McKiernan didn't have new ideas.

McKiernan was also perceived to be too accepting of the command-and-control structure in Afghanistan, which is split among individuals from various countries. McKiernan had said that the system was not ideal, but that he could work around it. Policymakers in Washington and other military officials, however, believed a change was needed to make the US more effective.