“We’re just not there yet,” the official said of reports that the U.S. has agreed to offer the weapons, equipment and support that was provided to Kurdish fighters who called in U.S. airstrikes to drive ISIS out of the Syrian town of Kobani last month. The U.S. and allies launched more than 700 air strikes against ISIS in and around Kobani from Aug. 8 to late January.

The defense official told NBC News that launching U.S. airstrikes to support the Kurds — a well-trained and disciplined military force — against an ISIS enemy confined to a relatively small area was a far more “controllable” situation than providing such support to the moderate Syrian rebels would be.

For now, the goal is to train and equip the rebels as a “defensive, not offensive, force” to protect their villages and surrounding territory, the official said. And the equipment and weapons would be provided “only after those rebels are fully vetted and trained” by the U.S. military.