The head of the Syrian Kurdish YPG militia said a U.S.-backed assault to drive the Islamic State from its de-facto capital Raqqa will begin at the start of April and that the YPG would take part, despite fierce opposition from neighboring Turkey.

A spokesman for the Pentagon said no decision had been made on the Raqqa offensive, part of a two-pronged attempt to dismantle the caliphate declared by the Islamic State group in parts of Syria and Iraq in 2014.

U.S.-backed forces, including the YPG, are closing in on the city, and President Donald Trump has said he wants to accelerate efforts to crush the hard-line militants, who are under siege by U.S.-backed Iraqi forces in the much larger city of Mosul.