Washington – U.S. presidential envoy to the anti-ISIS coalition Brett McGurk met with Kurdish allies in northern Syria last week, a State Department spokesperson said on Monday.

The visit came after the Turkish army had launched its military operation Euphrates Shield against ISIS and to stop Kurdish advancements, which left Washington in a tough position between its allies Ankara and Kurdistan.

Washington supports Syrian Democratic Forces (SDF), a coalition force dominated by the Kurdish Peoples Protection Units (YPG), in its fight against ISIS because it considers the SDF to be the most efficient group in fighting extremists.

Turkey considers the Democratic Union Party and YPG terrorist organizations and U.S. is trying to cease violence between Turkey and the Kurds.

With Washington’s support, SDF was able to liberate several towns from ISIS control. State Department spokesperson said McGurk promised “ongoing U.S. support for the SDF in the fight against ISIL [ISIS], while emphasizing the need for strict adherence to prior commitments,” referring to an agreement between Washington and Ankara that Kurdish forces would retreat to the east bank of the Euphrates on the conclusion of the operation to liberate the northern Syrian town of Manbij.

McGurk also met with Turkish officials last week, the spokesperson confirmed. They discussed Turkey’s Euphrates Shield operation and the U.S. support for it, as well as “planning for the Mosul campaign in Iraq, and closer U.S. and Turkish cooperation to accelerate ISIL’s ultimate defeat.”