The United States will send 560 more troops to Iraq to transform a freshly retaken air base into a staging hub for the long-awaited battle to recapture Mosul from Islamic State militants, Defense Secretary Ash Carter said on Monday. The new US forces should arrive in the coming weeks.

Most of the engineers, logistics personnel, security and communications forces will concentrate on building up Qayara air base, about 40 kilometers south of Mosul. They will assist Iraqi forces planning to encircle and eventually retake the biggest city anywhere that has fallen under IS' control.

The extremist group captured Mosul in the summer of 2014. It has used the city as a main headquarters since.