Turkey's foreign minister says it is a “big mistake” for Washington to support the Syrian Kurdish militants of the People's Protection Units (YPG), stressing that the matter has strained relations between the two NATO allies.

Mevlut Cavusoglu met with Turkish citizens at the Turkish consulate in New York on Sunday.

Washington has infuriated Ankara by announcing a plan for the formation of a Kurdish militant force in Syria near the Turkish border.

The plan prompted Turkey to launch a cross-border military operation on January 20 inside the Arab country, code-named Operation Olive Branch, with the declared aim of eliminating the YPG militants from northern Syria, particularly Afrin region.

The YPG forms the backbone of the so-called Syrian Democratic Forces (SDF), an anti-Damascus alliance of predominantly Kurdish militants supported by the United States.

Ankara views the YPG as a terrorist organization and the Syrian branch of the outlawed Kurdistan Workers’ Party (PKK), which has been fighting for an autonomous region inside Turkey since 1984.

“Despite knowing and acknowledging that (the YPG) is the same organization (as the PKK), seeing this cooperation as necessary is really a big mistake,” Cavusoglu said, adding that he would “broadly” discuss Ankara-Washington ties with US Secretary of State Mike Pompeo on Tuesday.

The Turkish top diplomat arrived in New York on Saturday to attend the 8th Global Forum of the United Nations Alliance of Civilizations (UNAOC) on partnerships for prevention and sustaining peace, which will be held at the UN headquarters on Monday and Tuesday.

Washington has been arming and training Kurdish militants under the banner of helping them fight the Takfiri Daesh terrorist group, but Syria and several other countries see ulterior motives behind the deployment.

The Syrian government has given a degree of authority to the Kurdish regions to run their own affairs. The US, however, has used the power vacuum to establish a foothold in those regions with the help of militants.

Ankara, one of Washington's key allies in the region, has repeatedly questioned the United States' deployment of heavy weapons in Syria despite the defeat of Daesh in much of the Arab country.

According to the Turkish government, US Defense Secretary James Mattis promised in 2017 that Washington would take back weapons from the Kurdish militants once Daesh had been routed.

Earlier this year, Turkish President Recep Tayyip Erdogan threatened to push Turkey's Afrin offensive against the YPG militants eastward to Manbij, where American forces are stationed, risking a confrontation between the NATO allies.

Syria has strongly denounced the presence of Turkish and US troops around Manbij.

Separately on Sunday, the state-owned Anadolu news agency cited Turkish Defense Minister Hulusi Akar as saying that he had told US Chief of Staff Joseph Dunford that Ankara expected Washington to halt its support for the YPG as soon as possible.