US President Donald Trump approved arming fighters from the Kurdish Peoples' Protection Units (YPG) in May – which is part of the Syrian Democratic Forces – drawing strong condemnation from Turkey.

Ankara said on Thursday that US Defence Secretary Jim Mattis promised to provide his Turkish counterpart with a monthly list of weapons handed to the YPG, with the first such inventory already sent.

In a letter to Turkish Defence Minister Fikri Isik, Mattis said that a detailed record of all equipment provided to the YPG was being kept and that all the weapons would be taken back after Islamic State was defeated, according to Turkish defence.

Mattis also said that Arab fighters would form 80 percent of the forces which will recapture Raqqa, the Islamic State's main urban base in Syria.



Once the mainly Sunni Arab city is taken, it will be held by Arab forces, the defence sources said he told Isik.

Washington and Ankara are bitterly at odds over US support for the YPG, a Syrian armed faction that acts as the main ground force in the Pentagon's plan to defeat the Islamic State group but that Turkey deems a front for the banned Kurdistan Workers' Party (PKK).

Turkey's concerns about the YPG were significant enough for Ankara to launch its own military operation inside Syria in August 2016, dubbed Euphrates Shield.

The operation had the dual goals of targeting IS and the Kurdish militia, particularly to prevent the YPG from controlling a contiguous strip of territory along the Syria-Turkey border.

The SDF – an Arab-Kurdish alliance formed in 2015 – spent seven months tightening the noose on Raqqa city before finally entering it last week.

An estimated 300,000 civilians were believed to have been living under IS rule in Raqqa, including 80,000 displaced from other parts of Syria.

Thousands have fled in recent months, and the UN humanitarian office estimates about 160,000 people remain in the city.