U.S. Defense Secretary Ash Carter said on May 7 that American troops have begun training a small, company-sized group of Syrian fighters to battle Islamic State militants.
Carter told a news conference that a second company-sized group of Syrian fighters would begin training soon.
The Pentagon chief said the unit that already has started training has about 90 personnel.
Earlier, officials said the U.S. military started training Syrian fighters in Jordan and would soon launch a similar program in Turkey.
The officials added that, besides Jordan and Turkey, other training sites are to become operational in Saudi Arabia and Qatar.
Officials spoke on condition of anonymity because they weren't authorized to discuss the training publicly.
The Obama administration says the program aims only to target Islamic State forces, since the United States is not at war with Syria.
But critics, including some rebel leaders, say the force risks sowing divisions and cannot succeed without directly targeting Syrian government forces.
The Pentagon declined to comment.
Based on reporting by Reuters and AP