U.S. National Security Advisor H.R. McMaster is expected to visit Turkey over the weekend, while Secretary of State Rex Tillerson will come next week, Turkish diplomatic sources confirmed Tuesday.

The visits by top U.S. officials come amid Turkey's Operation Olive Branch targeting the PKK terror group's affiliates in Syria, the Democratic Union Party (PYD) and the People's Protection Units (YPG), as well as Daesh in northwestern Syria's Afrin region.

The operation and the U.S.' presence in Syria's Manbij — where Turkey has vowed to extend it — are expected to be discussed during the meeting.

On Wednesday, Presidential Spokesperson Ibrahim Kalın said:

"The public questions whether the U.S. has plans to stay in the region in the long term due to ongoing U.S. support for PYD, even though President Trump personally promised President Erdoğan during phone calls that the support would end."

The U.S.' Syria policy, especially its military support for the Syrian Democratic Forces (SDF), which is dominated by YPG terrorists, has been a cause of tension between the two NATO allies.

Washington relies on the YPG to fight against Daesh on the ground, while Ankara argues that one terrorist group cannot be used to fight another terrorist group.