Islamic State is retrenching as Iraqi forces build up for an operation to retake the northern city of Mosul and some local militants desert the group, the commander in charge of the highly anticipated offensive said.

Thousands of Iraqi troops have deployed to the north with heavy weapons in recent weeks, setting up base alongside U.S. forces and troops from Iraq’s Kurdish autonomous region in Makhmour — a launchpad around 60 kilometers south of Mosul.

Although he described Islamic State as depleted, Nineveh Operations Commander Major General Najm al-Jubbouri said jockeying between the various forces preparing to take part in the battle for Mosul benefited the militants. […]