The chairman of the Joint Chiefs of Staff, Adm. Mike Mullen, said on television that security conditions in Iraq have improved dramatically, allowing the Iraqi government to take control of the country as U.S. troops withdraw.

Obama announced the withdrawal plan, which included leaving up to 50,000 troops in Iraq to provide stability, last week, almost six years after U.S.-led forces toppled Saddam Hussein in a vain hunt for weapons of mass destruction.

"I am very comfortable with the decision and strongly support the decision. And the president listened to all of us who were involved in this," Mullen said on CNN's "State of the Union."

During the U.S. presidential campaign, Obama had supported a 16-month timetable to pull troops out of Iraq.

Mullen said last summer it could be "very dangerous" to set a two-year deadline for withdrawing U.S. combat troops, which the Bush administration had bolstered with a surge in 2007.

"Conditions have changed fairly dramatically since last July. In particular, the military situation as a result the surge has gotten a lot better. Iraq security forces have improved," Mullen said on "Fox News Sunday."

"We just had a good set of elections in Iraq, well supported by the Iraqi security forces ... as those conditions continue to improve, we'll be able to execute this mission," he said.

But he would not call the U.S. involvement in Iraq a victory.

"I'm a little bit reluctant to talk specifically about winning and losing," he said.

Mullen said he was confident Obama would be flexible on the withdrawal timetable if conditions changed in Iraq, praising his willingness to listen to U.S. military commanders.

Obama's plan would pull combat troops out of Iraq by the end of August 2010. A residual force of 35,000 to 50,000 troops will remain to provide stability, train the Iraqi military, protect diplomats and conduct limited counterterrorism operations, a decision that disappointed Democratic lawmakers who favored a larger withdrawal.

"The conditions are set for the Iraqi government, the Iraqi people, to take over their own country and be responsible for it and have a very, very positive outcome," Mullen said.

The war in Iraq has been unpopular in the United States and enormously costly. It has taken the lives of 4,250 U.S. soldiers and damaged the country's standing in the world.

There are currently 142,000 U.S. troops overall in Iraq.