On Monday, President Obama fired the top American commander in Afghanistan.
The abrupt shake-up signals the U.S. is looking for a new approach to end the seven years of conflict in the war-torn country.
U.S. Army General David McKiernan has been relieved of his duties in Afghanistan.
The New York Times reported that he is the first general to be dismissed from a command in an active theater of combat since Gen. Douglas MacArthur during the Korean War.
McKiernan's replacement is Army Lieut. General Stanley McChrystal. McChrystal is a former special forces commander.
At a news conference held Monday, Defense Secretary Robert Gates said it is the right time for new leadership as the U.S. rethinks its strategy in Afghanistan.
"The focus here is simply on getting fresh thinking," Gates told reporters. "Fresh eyes on the problem and in how we implement the strategy and the mission going forward."
Despite seven years of U.S. involvement in Afghanistan, the country remains a battleground. Its problems include an unstable government, a flourishing opium trade and suicide attacks by supporters of al Qaeda.
President Obama has ordered an extra 17,000 combat troops be deployed to Afghanistan. By the year's end, the U.S. will have a total of 68,000 troops there and 130,000 in Iraq.