A suicide attack in the Taji area, north of the Iraqi capital, killed at least seven people and wounded 17 on Thursday, security and medical officials said.
It was not immediately clear if the target was the area's sprawling military base or an entrance to Taji itself, and the number of suicide bombers was unknown.
US military trainers are based at Taji, helping to instruct some 1,600 Iraqi soldiers in a six-week programme aimed at readying them to face the Islamic State (IS) jihadist group.
There was no immediate claim for the attack, but suicide bombings are a tactic almost exclusively employed by Sunni extremist groups in Iraq, including IS.
IS spearheaded a June offensive that overran much of Iraq's Sunni Arab heartland, sweeping security forces aside.
Iraqi troops, Kurdish forces, Shiite militias and Sunni tribesmen have since retaken some areas but the jihadists still holds significant territory, including three major cities.
A US-led coalition is carrying out air strikes against IS as well as advising and training both Iraqi federal and Kurdish forces.