Turkish media have confirmed that Foreign Minister Mevlut Cavusoglu met American Secretary of State Rex Tillerson in Paris on Tuesday as U.S. envoys arrive in Ankara to discuss the “struggle against terrorism,” a salient topic as Turkey continues its military invasion of Syrian Kurdish territories on its border.

The Turkish state-run Anadolu Agency reported Tuesday that Tillerson and Cavusoglu met on the sidelines of a larger multilateral summit on chemical weapons, citing a “source” who did not tell the outlet what the two discussed.

No issue is of higher priority than the Turkish invasion of the Syrian territory Afrin, however, which began over the weekend in an attempt to diminish the influence of Syrian Kurdish fighters. The Kurdish People’s Protection Units (YPG/YPJ) are American allies and oppose all jihadist elements in the country. They played a pivotal role in defeating the Islamic State in its “capital,” Raqqa, and continue to help in its reconstruction and serve as a force preventing groups like al-Qaeda from settling in the area.

The Turkish government considers the YPG terrorists indistinguishable from the Kurdistan Workers’ Party (PKK), a Marxist group the U.S. has designated a terrorist organization. Both the YPG and PKK contend that they have abandoned the Marxist ideology that they once held, though the YPG logo still carries a red star and Western Marxists have joined their ranks. The YPG have asserted that their ultimate goal in militarizing is to unite Rojava, or Syrian Kurdistan, under a Kurdish government.

Claiming that the Kurdish “horde of murderers” are seeking to carve an independent Kurdistan partially out of Turkish territory, Ankara launched an assault on YPG stronghold Afrin this weekend.

The State Department confirmed in a statement by spokeswoman Heather Nauert on Sunday that Tillerson spoke to Turkey’s foreign minister via phone to express that America is “very concerned about the situation in northwest Syria.” Tillerson reportedly ceded that Turkey has “legitimate security concerns”—without specifying what those are—and that the United States continues to “urge Turkey to exercise restraint and ensure that its military operations remain limited in scope.”

On Tuesday, the Turkish newspaper Hurriyet reported that U.S. Deputy Assistant Secretary for European and Eurasian Affairs Jonathan Cohen, along with unnamed defense officials, are meeting with Turkish counterparts in Ankara to discuss a variety of issues, including “the struggle against terrorism.” Hurriyet states that Turkish officials will update the Americans on the invasion of Syria, which they have dubbed “Operation Olive Branch.”

American officials have been careful not to anger the Turks while issuing no statement of support for their Kurdish allies. Defense Secretary James Mattis, who last week echoed the “legitimate security concerns” line, said Tuesday while traveling in Indonesia that Turkey’s invasion “disrupts” significant humanitarian aid relief flowing into aggrieved areas in Syria’s north.

“The violence in Afrin disrupts what was a relatively stable area of Syria. It distracts from international efforts to ensure the defeat of ISIS, and this could be exploited by ISIS and al-Qaida,” he said.

The Kurdish outlet Bas News also reports that General Joseph Votel, the head of U.S. Central Command, and USAID chief Mark Green visited Raqqa on Monday. While Raqqa is far from Afrin, it is currently being managed in part by the YPG.

The Trump administration has reacted relatively quietly to the Turkish invasion given that Ankara had initially argued that Washington made it impossible for Turkey not to deploy to Afrin. A spokesman for the U.S. coalition against the Islamic State announced the creation this month of a “Border Security Force” featuring YPG fighters in Syria, intended to keep would-be Islamic State terrorists from entering Syria via Turkey.

Turkish President Recep Tayyip Erdogan responded to the new force by calling them a “horde of murderers” and launching “Operation Olive Branch.”

Washington has repeatedly asserted it acknowledges “legitimate security interests” in this operation and Tillerson claimed the U.S. is not “building a border security force at all.”

We are here to protect our country’s rights within the scope of international law, without harming civilians or property,” Turkish Chief of General Staff Gen. Hulusi Akar said Monday, insisting that Turkish troops will remain in Syria “until the last terrorist is neutralized,” referring to the U.S.-allied YPG.

Erdogan himself has reportedly compared the operation to the conquest of Constantinople.

Erdogan supporters claim that the operation is necessary because the United States is Turkey’s enemy. Hard-line Erdogan supporter Ibrahim Karagul, editor-in-chief of the newspaper Yeni Safak, wrote this week, “Saw the example of the U.S. hitting Turkey with a terrorist organization on July 15, 2016. It is repeating this a second time in northern Syria.” Karagul is referring to the failed coup against Erdogan in 2016, which he appears to believe was orchestrated by the United States.

While Karagul claims the response is a necessary one to the “border security force,” his own newspaper claimed in a report Tuesday that Erdogan had been planning an invasion of Afrin “for three months.” The contested “border security force” was announced two weeks ago.

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