Turkish President Recep Tayyip Erdogan on Tuesday denounced the United States for holding joint military patrols near the Turkish border in northern Syria with fighters from the Kurdish People’s Protection Units (YPG).

“This is not an acceptable thing. This can cause serious negative developments on the order. I believe Mr. [U.S. President Donald] Trump will stop this,” the Turkish leader declared, referring to joint U.S.-YPG patrols on Sunday, according to Hurriyet Daily News.

Erdogan and President Trump are expected to meet in Paris on November 11 as European leaders mark 100 years since the end of the first world war.

“The U.S. troops in the east of Syria launched a joint patrol mission with the YPG on the Turkish border after the Turkish army hit the YPG positions in [the] east of [the] Euphrates,” Hurriyet notes. “Turkey considers the YPG as the offshoot of the PKK and therefore as terrorists.”

Despite Turkey’s concern over the YPG, the United States continues to lend support to the Kurdish fighters, arguing that they are the best local force to combat the Islamic State (ISIS/ISIL).

U.S.-led coalition spokesman Sean Ryan reportedly said Sunday’s patrol in YPG-held territory near the Turkish border was the second in a week, after a first one by U.S. forces on Friday, the Agence France-Presse (AFP) news agency revealed.

“The U.S. forces’ assurance patrols enable us to maintain safety and security in the region,” he said, but are not carried out “on a regular basis.”

Mustafa Bali, a spokesman for the YPG-led Syrian Democratic Forces (SDF), told AFP that the joint U.S.-Syrian Kurds patrols on Sunday directly stem from renewed clashes between Kurds and Turkey.

“They are not routine patrols. They are directly linked to these threats. The objective is to call on Turkey to stop its aggression,” he declared.

Last week, Turkey announced a new offensive against the YPG in its stronghold east of the Euphrates, in northern Syria.

The YPG forms the central part of the U.S.-allied SDF that Washington is backing with weapons, air support, and around 2,000 special forces troops on the ground in the fight against ISIS, according to France 24.

“Turkey has been firing across the border for five days in preparation for what President Recep Tayyip Erdogan says will be an offensive soon to crush the Kurdish forces along the breadth of the Turkish frontier,” France 24 noted on November 2.

Citing the Turkish shelling, the SDF reportedly paused its anti-ISIS operations.

Ankara was bombing the Syrian Kurds as U.S. and Turkey began to conduct joint patrols in Syria’s Manbij region last Thursday.

In June, the U.S. and Turkey reached an agreement to hold joint patrols and withdraw the YPG fighters from Manbij to reduce tensions.

The joint U.S.-Turkey patrols in Manbij came after Military Times reported that Ankara-allied fighters attacked an American military unit on October 15.

Although the U.S. and YPG claim the Kurds have pulled out of the city, Ankara has repeatedly complained that the group still has a presence there and has threatened military action.

France 24 noted:

Turkish military advances into northern Syria over the past two years have put US forces directly in the path of advancing troops from Turkey, Washington’s main NATO ally in the region. The two countries have been working to avert direct confrontation, even as Turkey aims to crush the Kurdish YPG militia.
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Over the past two years, Turkish forces have already swept into Syria to push YPG fighters out of territory west of the Euphrates in two separate military campaigns. Past offensives halted at the banks of the river, in part to avoid direct confrontation with the United States.

However, Turkey is pushing directly towards U.S. troops and their YPG allies in northern Syria, east of the Euphrates.

With the help of the United States, Syrian Kurds maintain control over large swathes of northern Syria, near the Turkish border.

U.S. support for the YPG has strained the relationship between NATO allies Ankara and Washington.

AFP learned from that the U.S. State Department that the Trump administration had been in touch with both the SDF and Turkey to push for de-escalation.