The PYD/YPG is the Syrian branch of the PKK terror group, the American Special Representative for Syria James Jeffrey said Thursday.
He spoke at a panel at the Defense One Summit, which brings top military, foreign policy and intelligence leaders to Washington to discuss American security throughout the world.
Jeffrey said U.S. operations in Syria could not be done without the "active participation, coordination, and cooperation of Turkey."
The U.S. is not able to function in the northeastern region of Syria while fighting Daesh forces at the same time, and to do both a local partner is needed, according to Jeffrey.
"That local partner since 2014 has been the PYD, which is the Syrian offshoot of PKK, but we have not designated it as a terrorist organization which we did with the PKK,” said Jeffrey, referring to the political wing of the YPG.
In its more than 30-year terror campaign against Turkey, the PKK -- listed as a terrorist organization by Turkey, the U.S. and the EU -- has been responsible for the deaths of 40,000 people.
Turkey has repeatedly told Washington that the PYD/YPG is not any different from the PKK and partnering with one terrorist organization to defeat another would not yield any result.
He said that the U.S. is still in the northeast region of Syria to defeat Daesh terrorists, remove Iranians out of the area and ensure the political process in the country.
Turkey agrees with all three points but the U.S. added "some conditions" and did not do a proper job of explaining them to Ankara, he said without mentioning what those conditions were.
Jeffrey said without Turkey’s help, the U.S. mission in Syria would be over.