The U.S. military will remain in northern Syria even after Daesh terrorists are cleared from the region, and it has set up bases in northern Syria that may be alternative to Turkey, the U.S.-backed Syrian Democratic Forces (SDF) spokesman Talal Silo was quoted as saying by Reuters.

The SDF, which is predominantly led by the PKK's Syria affiliate Democratic Union Party (PYD) its armed People's Protection Unit (YPG), is backed by the U.S. military under pretext of fighting Daesh in Syria.

The United States has a strategic interest in staying, the SDF spokesman told Reuters.

"They have a strategy policy for decades to come. There will be military, economic and political agreements in the long term between the leadership of the northern areas [of Syria] ... and the U.S. administration," he said.

"They [recently] referred to the possibility of securing an area to prepare for a military airport. These are the beginnings – they're not giving support just to leave. America is not providing all this support for free," he added.

He suggested northern Syria could become a new base for U.S. forces in the region.

"Maybe there could be an alternative to their base in Turkey," he said, referring to the İncirlik Air Base.

The head of the YPG said last month that the United States had established seven military bases in areas of northern Syria controlled by the YPG or SDF, including a major air base near Kobani, a town on the border with Turkey.

The U.S.-led coalition against Daesh has deployed forces at several locations in northern Syria. It has supported the SDF with airstrikes, artillery, and special forces on the ground, despite the SDF's link to the PKK, which is on the list of banned groups by the U.S., EU and Turkey, causing intense tensions with Ankara.

The U.S. says supporting the SDF is the only alternative for defeating the Daesh terrorist group; whereas Turkey says an alternative should be formed through local Arab tribes backed by countries in the region instead of supporting a terrorist group.

Furthermore, Turkey considers the PYD and the YPG to be Syrian affiliates of the PKK.

The PYD has come under the spotlight for its crimes against Arab and Turkmen locals in northern Syria, as part of its attempt to implement demographic changes in the region.

Moreover, Ankara says that the arms delivered to the YPG will ultimately be transferred to the PKK, due to their "organic" organizational links, and used against Turkey.

Asked about long-term strategy, Col. Ryan Dillon, spokesman for the coalition, referred Reuters to the Pentagon. He said there was "still a lot of fighting to do, even after ISIS [Daesh] has been defeated in Raqqa."

"Our mission ... is to defeat [Daesh] in designated areas of Iraq and Syria and to set conditions for follow-on operations to increase regional stability," Dillon said, without elaborating.