WASHINGTON - President Barack Obama is offering some of the first public details about the activities of U.S. special forces that have been sent to fight the Islamic State group. 

He says those forces in Syria have started helping local groups cut off supply lines used by the militants, and put pressure on the city that is the group's unofficial "capital" in Syria.

In an effort to encourage allies to contribute more to the fight, Obama says he's sending Defense Secretary Ash Carter to the Middle East. 

Obama spoke at the Pentagon after meeting there with his National Security Council. 

The administration announced in late October that Obama had approved sending up to 50 special operations troops to Syria on the first open-ended mission by U.S. ground forces in Syria. Until now, U.S. officials had refused to say whether the American commandos had begun their mission.