US Defense Secretary Ash Carter said Saturday that as many as 200 more American troops are being sent to Syria to help Kurdish and Arab fighters capture the ISIS group’s key stronghold of Raqqa.

The extra troops will include special operations forces and are in addition to 300 US troops already authorized for the effort to recruit, organize, train and advise local Syrian forces to combat ISIS.

Addressing a security conference in Bahrain, Carter said the extra troops will help the local forces in their anticipated push to retake Raqqa, the de facto capital of the extremist group’s self-styled caliphate, and to deny sanctuary to ISIS after Raqqa is captured.