Iraq and Syria declared victory over ISIS in late 2017, but the U.S. and Turkey have resisted calls to withdraw their forces.
Groups the U.S. is considering labeling terrorist organizations have officially become part of the Iraqi military that Washington sponsors.
The Iraqi prime minister rejected the Kurdish vote for independence and parliament has given him military power to oppose it.
Despite being largely defeated in its former Iraqi stronghold of Mosul, the Islamic State militant group is still gaining territory amid new clashes.
Any move northwards would take them back closer to Iraq's border with Turkey, but officials did not say where they were going.