The Bush administration is considering changing its war strategy in Afghanistan in light of rising levels of violence and an increasingly complex insurgent threat, Defense Secretary Robert Gates said Thursday.

"You have an overall approach, an overall strategy, but you adjust it continually based on the circumstances that you find," Gates said in an interview with a group of reporters at a London hotel. "We did that in Iraq. We made a change in strategy in Iraq and we are going to continue to look at the situation in Afghanistan."

Pressed for more details about the review of Afghan strategy, Gates would say only, "We're looking at it."

Gates visited Afghanistan on Wednesday and flew to London for NATO consultations.

He did not reveal whether the White House has launched a formal review of its war strategy. But his remarks indicated that the administration sees a need to make some adjustments as progress there remains slow.

The Joint Chiefs chairman, Adm. Mike Mullen, told a House committee last week that he had commissioned a study of Afghan strategy to incorporate the complexities presented by rising unrest and insurgent activity in Pakistan. Mullen also publicly questioned whether the United States is winning in Afghanistan.

Gen. David McKiernan, the senior U.S. general in Afghanistan, told reporters on Tuesday at his Kabul headquarters that he believed the current strategy was adequate but that he needed more U.S. troops and other resources to properly execute it. He said he needs more than 10,000 extra American ground troops in 2009, in addition to the reinforcements already announced by the Pentagon.

In the interview Thursday, Gates also was asked about a stalemate in U.S. efforts to complete negotiations with the Iraqi government on a legal framework to govern the presence and role of U.S. troops after December, when a U.N. mandate is set to expire. He said the U.S. negotiating team was returning to Baghdad to resume talks and that they had brought with them some new ideas on how to bridge the negotiating gap.

He offered no details but said the new American proposals were intended to resolve differences with the Iraqis over the extent of Iraqi legal jurisdiction over U.S. personnel in the country and over detainees.

Gates met with Iraqi officials in Baghdad on Monday.

Gates also said that at a NATO meeting here Thursday and Friday he would raise the issue of how to share the cost of a planned doubling in the size of the Afghan national army. He said building up the capacity and effectiveness of Afghanistan's own security forces is "ultimately the exit strategy for all of us."

The United States has about 33,000 troops in Afghanistan, and President Bush has ordered an Army brigade of about 3,700 soldiers that had been preparing to deploy to Iraq to instead go to Afghanistan in January.

Bush also announced last April at a NATO summit meeting in Bucharest, Romania, that the United States would send even more troops to Afghanistan later in 2009, beyond his term in office, when ends in January.

Gates mentioned that Bush pledge on Thursday and said, "I expect his successor will meet that commitment."

Gates noted that violence has been on the rise in Afghanistan for the past two years, in part because of cross-border attacks from Al Qaeda, Taliban and other extremist elements that find refuge in neighboring Pakistan. That has made it harder for U.S. and allied troops to improve security, which Gates said has restricted gains in other vital areas such as weeding out government corruption and developing the economy.

"We see some lessons to be learned from Iraq in terms of the need to establish security as a precondition or economic development and better governance. That means more forces," he said. "But I think we are in complete accord with our European allies that the military side of this is only one piece of the solution."

Violence has been on the rise in eastern and southern Afghanistan, and Gates said it reflects in part an increasingly complex set of insurgent components, beyond the Taliban rebels who had ruled Afghanistan and granted a refuge in the country for Usama bin Laden prior to the terrorist attacks of Sept. 11, 2001.

"It's not a centrally controlled Taliban insurgency against the government," he said. "It's a number of different challenges against the government."

Gates also told reporters that he believes Britain intends to add more troops in Afghanistan, but he offered no numbers and said he was not sure the government here had made a final decision.