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Symbolism and souvenirs: Ceremony marks end of US mission in Iraq

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General Lloyd Austin, Commander of US Forces in Iraq, retires the United States Forces Iraq flag during a casing ceremony on Dec. 15, 2011.

Mario Tama / Getty Images

American soldiers look on as a military band performs after the flag casing ceremony on Dec. 15, 2011.

Mohammed Ameen / Reuters

U.S. military personnel pose for a souvenir picture before the start of a ceremony marking the end of the U.S. military engagement in Iraq, at the former U.S. Sather Air Base near Baghdad on Dec. 15, 2011.

Pablo Martinez Monsivais / AFP - Getty Images

The US flag, the Iraqi flag, and the US Forces Iraq colors are carried, during a flag-lowering ceremony marking the end of the US mission in Iraq on Dec. 15, 2011.

Pablo Martinez Monsivais / AFP - Getty Images

US military personnel in Baghdad bow their heads during the flag-lowering ceremony on Dec. 15, 2011.

Mario Tama / Getty Images

A U.S. soldier walks past cables for media use before the start of the ceremony on Dec. 15, 2011.

msnbc.com staff and news services report:

Secretary of Defense Leon Panetta marked the end of the U.S. war in Iraq at a highly symbolic ceremony Thursday.

"Let me be clear, Iraq will be tested in the days ahead -- by terrorism, by those who would seek to divide," Panetta said.

"Challenges remain but the United States will be there to stand with the Iraqi people. We are not about to turn our backs on all that has been sacrificed and accomplished."

Read more in the story 'A new chapter': US shuts down Iraq war.

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