Washington(CNN) The United States recently delivered a new supply of fresh ammunition to Syrian Arab fighters battling ISIS in northern Syria, a U.S. official tells CNN.
It is the third such shipment since the United States shifted away from looking to train Syrian rebel forces outside of the country and began providing weaponry directly contingent on battlefield progress against ISIS.
The shipment, delivered over land from a position in northern Iraq, consisted only of ammunition, and was described by the official on the condition of anonymity to protect operational security of the mission.
The Syrian Arabs, made up of approximately 5,000 fighters, continue to deny ISIS significant territorial gains in the north, and push south from their positions to take on ISIS with the goal of eventually pushing on ISIS's self-declared capitol of Raqqa.
U.S. military officials have said they would continue such shipments if the fighters used the ammunition in the battle against ISIS and continued to show progress in their efforts.
The first such shipment was air-dropped into northern Syria by the U.S. military in October, and then a second shipment was delivered over land last month.
Reuters first reported about the shipment on Wednesday night.