BAGHDAD (AP) — The Pentagon says an explosive device has killed a U.S. service member outside Mosul.

The Pentagon on Saturday did not provide any further details, stating further information would be released as appropriate.

Saturday's incident marks the second American military fatality since the start of the Mosul operation against the Islamic State group more than six months ago.

The Pentagon has acknowledged more than 100 U.S. special operations forces are operating with Iraqi units, with hundreds more playing a support role in staging bases farther from the front lines.

There are now more U.S. forces in Iraq than any time since the 2011 U.S. withdrawal, marking an intensifying war as Iraqi forces and the U.S.-led coalition work to push IS out of the last pockets of territory it controls in Iraq.