Iraq Withdrawal Photos: U.S. Officially Ends War

On Thursday the United States officially ended its war in Iraq, nine years after it first invaded the country. In a closing ceremony attended by Defense Secretary Leon Panetta, U.S. troops took down the flag of the American Army in Iraq.

"After a lot of blood spilled by Iraqis and Americans, the mission of an Iraq that could govern and secure itself has become real," Panetta said. "You will leave with great pride -- lasting pride," he told the troops.

Yet many feel the day isn't cause for celebration. More than a hundred thousand Iraqis and nearly 4,500 U.S. troops have died since the start of the war in 2002. The U.S. spent at least $805 billion on a war that has left Iraq divided along sectarian lines and facing political deadlock and deep insecurity.

The last American combat troops will leave Iraq on December 31. A small contingent of soldiers will stay behind to guard the American embassy in Baghdad, while some 4,000 private security companies are expected to continue operations in the country.

Take a look at photos of U.S. troops leaving Iraq: