Türkiye has summoned the American ambassador to Ankara and demanded an explanation over US Chairman of the Joint Chiefs of Staff Mark Milley's visit to the regions occupied by the YPG/PKK terror group in northeastern Syria.

Diplomatic sources told Anadolu Agency (AA) that Ambassador Jeff Flake was summoned to the Turkish Foreign Ministry on Monday over Milley's visit.

Sources also said Flake was asked to give an explanation about the visit.

Joint Staff spokesman Col Dave Butler told AA that "General Milley visited Northeast Syria today to meet with (US) commanders and troops."

“While there he received updates on the counter-ISIS mission, inspected force protection measures and assessed repatriation efforts for the Al Hol refugee camp,” Butler added.

US support for the YPG has long strained relations between Ankara and Washington.

In its almost 40-year terror campaign against Türkiye, the PKK – listed as a terrorist organisation by Türkiye, the US, and the EU – has been responsible for the deaths of over 40,000 people, including women, children, and infants.

The YPG is the Syrian affiliate of the PKK terror group.

READ MORE:Turkish forces 'neutralise' three PKK/YPG terrorists in northern Syria