US Army regulars leave Iraq President Barack Obama kept his promise to voters, the U.S. military and the Iraqis. On the night of August 19, mechanized columns of the 4th Brigade of the 2nd Infantry Division, the last of the US combat units in Iraq, crossed the Iraqi border with Kuwait. The soldiers did not hide their feelings: they unfurled the American flag, shouted joyfully, took photographs for memory and fired tracer bursts into the air.