WASHINGTON (Reuters) - The United States said on Tuesday it started distributing arms to Syrian Kurdish militia battling to help retake the city of Raqqa from Islamic State, moving ahead with a war plan that has angered NATO ally Turkey.

FILE PHOTO: Kurdish fighters from the People's Protection Units (YPG) stand near U.S military vehicles in the town of Darbasiya next to the Turkish border, Syria April 29, 2017. REUTERS/Rodi Said

Pentagon spokesman Major Adrian Rankine-Galloway said the Kurdish fighters received small arms and vehicles from the U.S. military. He believed the arms were distributed earlier on Tuesday.

Another U.S. official, speaking on condition of anonymity, said the distribution of the arms had started in the past 24 hours, based on authority given by President Donald Trump earlier this month.

There was no immediate reaction from Turkey, which has warned the United States that its decision to arm Kurdish forces fighting Islamic State in Syria could end up hurting Washington.

Turkey views the YPG as the Syrian extension of the outlawed Kurdistan Workers Party, or PKK, which has fought an insurgency in southeast Turkey since 1984 and is considered a terrorist group by the United States, Turkey and Europe.

The United States regards the YPG as a valuable partner in the fight against Islamic State militants in northern Syria.

Washington says that arming the Kurdish forces is necessary to recapturing Raqqa, Islamic State’s de facto capital in Syria and a hub for planning attacks against the West.

U.S. officials have told Reuters that the United States was also looking to boost intelligence cooperation with Turkey to support its fight against the PKK.

It was unclear if the effort would be enough to soothe Turkey, however.

Ankara worries that advances by the YPG in northern Syria could inflame the PKK insurgency on Turkish soil. It has also voiced concern that weapons given to the YPG would end up in the hands of the PKK.