After numerous delays, the U.S. military has started training dozens of Syrian fighters to help confront Islamic State militants inside the war-torn country, Defense Secretary Ashton Carter said Thursday.
U.S. officials have vetted and cleared more than 400 Syrians to begin the six-week course. They will receive pay, basic training and light arms at sites in Turkey, Jordan, Saudi Arabia and Qatar.
About 90 Syrians have begun training, and a second group will "begin training in the next few weeks," Carter said.
The Times reported Monday that the program, which President Obama announced nearly a year ago, had yet to actually train any Syrian forces to join the battle against Islamic State.
Carter acknowledged that finding, training and arming reliable fighters poses significant challenges given the ferocious multi-sided civil war in Syria.
"This is a complex program," Carter told reporters at the Pentagon. "It's going to have to evolve over time. I think it's fair to say … that it will need to prove itself."
The White House wants the proxy force to target Islamic State militants, while many of the Syrian rebels -- and the four host nations -- want to focus on ousting Syrian President Bashar Assad.
"They are being trained and equipped to fight ISIL," Carter said, using an acronym for Islamic State. "That'll be their principal mission."
It's still unclear if the Pentagon will order airstrikes or provide evacuation and medical support to help any Syrian forces it sends into the field.
"We have not yet determined all the rules of engagement," Carter said, adding that the U.S. military is inclined to support the Syrians.
A multinational coalition led by the U.S. began bombing Islamic State positions in Iraq last August, and in Syria last September. They have flown nearly 4,000 missions in all.
Congress approved $500 million for the training program in October.
The Pentagon said it intends to train and equip 5,400 Syrians a year for the next three years. About 3,750 volunteers are in the screening and vetting process, officials said.