Faced with almost certain defeat, some senior Islamic State leaders are slipping out of Mosul as Iraqi and Kurdish forces close in on the city. Foreign fighters who can’t blend in to the local population have little choice but to stay and fight, the U.S. general in command of ground forces said Wednesday.

“We’ve got indications that leaders have left. A lot of foreign fighters we expect will stay because they’re not gonna be able to exfiltrate as easily as some of the local fighters or the local leadership,” Maj. Gen. Gary Volesky, the 101st Airborne Division Commander, told reporters at the Pentagon in a briefing piped in from Baghdad.