SULAYMANIYAH, Iraq — The United States has begun airdropping pallets of weapons and ammunition to the Syrian Kurdish militia and allied Arab forces in northern Syria.

“They started dropping the arms in Rojava early this morning,” said Polat Can, spokesman for the Democratic Union Party (PYD), the Kurdish political party whose armed wing, with the help of U.S. bombing, has pushed the Islamic State from as much as 6,800 square miles of northern Syria. Rojava, or “west Kurdistan,” is the name the PYD uses to refer to northern Syria’s Kurdish areas.

Meanwhile, Russia aircraft continued to bomb targets in Syria’s west, far removed from the main operating areas of the Islamic State. The United Nations’ special envoy for Syria, Staffan de Mistura, stepped up efforts to find a diplomatic solution to the conflict, scheduling visits to Moscow and Washington. He said his first priority was to make certain that Russian military intervention doesn’t spread the conflict.

The Pentagon confirmed that C-17 transport aircraft had dropped 45 tons of arms in 100 pallets to groups inside northern Syria. But it said the initial drop late Sunday was to benefit “Arab groups,” a nod to Turkish concerns about U.S. support for the PYD’s Popular Protection Units, or YPG, militia.

The Pentagon last week announced that it had ended its $500 million program to train and equip vetted Syrians to fight the Islamic State, and said the remaining money would be used to supply weapons to armed groups already in Syria that had success against the Islamic State.

Can said the weapons dropped in Rojava included assault rifles, mortars and ammunition – but no TOW anti-tank missiles nor anti-aircraft weapons. He said the Kurdish forces would distribute weapons to Arab units affiliated with the YPG.

“Everyone will take arms. We believe in sharing,” he said. The YPG’s ability to provide arms “is why some Arab tribes are joining us.”