Deadline for U.S. Troop Withdrawal Arrives

UNDATED—Tuesday marks a turning point in U.S. Involvement in Iraq.

Tuesday is the deadline for U.S. forces to withdraw from Baghdad and urban areas and hand over security to Iraqi forces. Meanwhile, military officials report four soldiers were killed in combat in Baghdad Monday.

"In days to come you will find most soldiers out in the countryside, fighting alongside our Iraqi army and police comrades," says Multi-National Commander, Daniel Polger.

While Iraqi forces showcase their training, attacks have spiked, 250 people were killed last week in bombings in mainly Shiite areas. However, experts say Iraqi troops have made progress.

"The training wheels have been coming off for a while. The process is gradual and that's the good thing about it," says Michael O'Hanlon, Brookings Institution.

About 131,000 U.S. troops will stay in cities advising Iraqi forces and ready to call in reinforcement if needed, but now, the decision to call for help will be up to Iraqis. Administration officials say combat forces will start to come home early next year, withdrawing all of them by August.

NBC's Brooke Hart reports from Washington, D.C.