U.S. forces have positioned in four districts in eastern Mosul to oversee the implementation of new combat plans as Iraqi forces become closer to retake that region from Islamic State militants, military sources say, IraqiNews quoted an Iraqi army officer in Mosul speaking to London-based al-Quds al-Arabi newspaper as saying.

The bases were surrounded by tight security measures that deny access even to Iraqi troops and became under around-the-clock aerial watch as the Iraqi army’s Golden Division, a special operations force, prepares to carry out a newly-devised U.S. combat plan, the IraqiNews report continued.

The districts chosen as location for the new bases were al-Quds, Saddam, Zohour and Gogjali, according to the officer.

The US has advised Iraqi forces to concentrates all attacks on one district at a time rather than spreading forces across many districts.

Though displaced families from those districts were barred from returning home by Iraqi forces who feared attacks by ISIS militants, the U.S. forces allowed the families to return, according to the source.