Supplied Syrian Rebels Win Back IS Territory

"The Syrian Arab Coalition showed us valor", he said. It summoned the USA and Russian ambassadors over the claims of a weapons delivery to the YPG.

On October 12, the United States air-dropped about 50 tons of ammunition to the Syrian Arab Coalition.

"As they follow through on commitments they make to take the fight to ISIL [Islamic State], we will provide additional support", Smith said.

The group "conducted an attack... driving ISIL back", Warren said by videoconference from Baghdad, using an alternate acronym for IS.

Whether future airdrops will also include weapons has yet to be decided, he said. "We're going to continue to operate this way as long as it works well".

GETTYA Russian SU-34 bomber

Warren said the USA would continue to supply the Syrian Arab Coalition with ammunition, although he did not say when the next airdrop would occur.

Credit: Ahmet Sik/Getty Images Kurdish People's Safety Units, or YPG, fighters rest in Tal Abyad, Syria on Jun. 19, 2015.

The Pentagon's announcement came just a day after The New York Times published an article calling into question the capabilities of the SDF and the Syrian Arab Coalition.

"We have seen that".

The al-Hawl offensive was supported by 17 air strikes that included A10s (anti-tank aircraft) and an AC-130 Specter gunship (ground attack aircraft) from Incirlik, Turkey, Warren said.

The spokesman said the operation had pitted "well over a thousand friendly forces" against "several hundred enemies" in the vicinity, after heavy U.S. airstrikes had cleared the way.

While the recent gains are good news for the coalition, it is too soon to say the adjusted Syria plan is "working", according to Michael O'Hanlon, a defense policy expert with the Brookings Institution, a public policy research group in Washington. "But we're encouraged by what we see, and ... we intend to reinforce success".

Washington's strategy in Syria has shifted from trying to train fighters outside the country to supplying groups headed by US-vetted commanders.

Turkey regards Syrian Kurdish YPG units in the same category as the outlawedKurdistan Workers' Party (PKK), with which the state has been in an armed fight for over 30 years, with a death toll of over 40,000 from both the camps.

The White House announced on Friday that US President Barack Obama had authorized the first sustained deployment of special forces to Syria, reversing a long-standing refusal to put United States boots on the ground.

U.S. officials have stressed the forces would not engage in front-line combat.