Soldier of U.S. Army 173rd Airborne Brigade prior to an air analysis mission near an oil and gas separation plant at the Baba Gurgur oil field outside northern Iraq's town of Kirkuk in May 2003. Shamil Zhumatov/Reuters/Landov hide caption

itoggle caption Shamil Zhumatov/Reuters/Landov

Brig. Gen. Mohammad Ali Mughdeed talks to the men he commands to protect the Mosul dam, a critical piece of infrastructure that supplies water and electricity. The dam recently fell to the Islamic State in Iraq, but Kurdish forces say they've retaken it, a claim that could not be verified. Alice Fordham/NPR hide caption

itoggle caption Alice Fordham/NPR

The American flag, Iraqi flag, and the U.S. Forces Iraq colors are carried during ceremonies in Baghdad today marking the end of the U.S. military mission in Iraq. Pablo Martinez Monsivais/pool/AP hide caption

itoggle caption Pablo Martinez Monsivais/pool/AP

Baghdad's traffic, choked by hundreds of checkpoints, slows to a crawl while security forces inspect vehicles for weapons and explosives. Lynsey Addario/National Geographic hide caption

itoggle caption Lynsey Addario/National Geographic