US Defense Secretary Ash Carter saidon Saturday that as many as 200 more American troops are being sent to Syria to help Kurdish and Arab fighters capture the Islamic State 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, organise, train and advise local Syrian forces to combat IS.
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 IS after Raqqa is captured.
He said President Barack Obama approved the troop additions last week.
"These uniquely skilled operators will join the 300 US special operations forces already in Syria, to continue organizing, training, equipping, and otherwise enabling capable, motivated, local forces to take the fight to ISIL,"Carter said in his address to the IISS Manama Dialogues in the Bahraini capital, Manama.
"By combining our capabilities with those of our local partners, we've been squeezing ISIL by applying simultaneous pressure from all sides and across domains, through a seriesof deliberate actions to continue to build momentum," he said.
The military push in Syria is complicated by the predominant role played by local Kurdish fighters, who are themost effective US partner against IS in Syria but are viewedby Turkey -- a key US ally -- as a terrorist threat.
A senior defence official said the troop boost announcedby Carter will give the US extra capability to train Arab volunteers who are joining the Raqqa push but are not welltrained or equipped. The official spoke on condition ofanonymity to discuss details of internal Pentagon planning.