The U.S.-led coalition fighting the Islamic State group in Syria and Iraq says that a U.S. service member has died of suspected natural causes in northern Syria.

A statement released by the coalition on Wednesday gives no other details and says that further information will be released as appropriate. The American military does not release names of fallen soldiers before the next of kin and family are notified.

The U.S. has significantly increased its military footprint in northern Syria in support of local Kurdish-led opposition fighters as they prepare for an assault on the Islamic State’s self-proclaimed capital of Raqqa.

There are hundreds of U.S. special forces, Marines and army rangers in northern Syria.

(AP)