US combat mission in Iraq comes to an end
After seven and a half years, the American military's combat mission in Iraq formally ends on Tuesday.
But just under 50,000 troops will remain to train and advise Iraqi security forces.
One focus of attention is the northern city of Kirkuk which some fear could become a future flashpoint when American forces all depart at the end of next year.
Both Kurdish and Arab communities claim territory in the area.
Gabriel Gatehouse has spent time with the US Army in Kirkuk.