U.S. Defense Secretary Robert Gates is replacing the commander of American and NATO forces in Afghanistan, General David McKiernan.
Secretary Gates told reporters at the Pentagon he has asked for McKiernan's resignation and is recommending Army Lieutenant General Stanley McChrystal to command NATO and U.S. troops in Afghanistan.
Gates says the American mission can and must do better in Afghanistan and requires new thinking from military leaders.
"Today we have a new policy, set by our new president," said Gates. "We have a new strategy, a new mission and a new ambassador. I believe that new military leadership also is needed."
Gates thanked McKiernan, who arrived in Afghanistan 11 months ago, for what he called a long career of distinguished service.
He did not fault McKiernan's actions in Afghanistan.
General McChrystal is a former commander of special operations forces and is experienced in leading the kind of counterinsurgency combat Pentagon officials believe is necessary to defeat the Taliban, al-Qaida and other militant groups.
Secretary Gates also announced that another senior officer, Lieutenant General David Rodriguez, will be McChrystal's deputy.
The new plan by the Obama administration for Afghanistan and Pakistan calls for a military push to reverse deteriorating security, a surge in civilian aid and development assistance, and possible reconciliation between the Kabul government and some members of the Taliban.
U.S. President Barack Obama has ordered the deployment of 17,000 more combat troops to Afghanistan and 4,000 U.S. trainers and non-combat soldiers to help Afghanistan with reconstruction.
Secretary Gates says he wants new ideas from his new generals in Afghanistan.
"Well I think that is the challenge that we give to the new leadership," he said. "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? How can we be more effective?"
Secretary Gates urged members of the U.S. Senate to confirm General McChrystal as soon as possible.