WASHINGTON — The top American military officer met Tuesday with his Russian and Turkish counterparts to discuss how to avoid an unintended confrontation as forces from all three nations operate on an increasingly crowded battlefield in northern Syria.
The unusual three-way meeting was held in Antalya, Turkey. It brought together Gen. Joseph F. Dunford Jr., the chairman of the Joint Chiefs of Staff; Gen. Valery V. Gerasimov, the chief of the Russian general staff; and their Turkish counterpart, Gen. Hulusi Akar.
The major purpose of the session was to discuss “the fight against all terrorist organizations in Syria” and “the importance of additional measures for de-conflicting operations,” a spokesman for General Dunford said in a statement.
The situation in northern Syria has become increasingly tense in recent days. Supported by American and Russian airstrikes, Turkish forces and Syrian militias supported by Turkey recently succeeded in taking the town Al Bab from the Islamic State, also known as ISIS or ISIL.
But Turkey’s main worry is not ISIS but ensuring that Syrian Kurds do not establish a ministate in northern Syria. That has spurred fears that Turkish troops and their allies in the Syria opposition might move to seize Manbij, a town in northern Syria that was taken from ISIS by Syrian Arab and Kurdish militias backed by the United States.
The fighters defending Manbij do not believe that the Turkish posture is mere saber-rattling. Abu Amjed, the head of the Manbij Military Council, said in an interview last week that his fighters were being shot at by Turkish troops and that he considered Turkey to be more of a threat than ISIS.
As the situation escalated, the Manbij Military Council has tried to pre-empt any Turkish offensive by striking a deal with Russia to turn nearby villages under its control over to Syrian government forces loyal to President Bashar al-Assad. As part of that deal, a Syrian government convoy with humanitarian aid began to make its way to Manbij, escorted by Russian armored vehicles, which halted just short of the town.
At the same time, American troops in Stryker fighting vehicles and armored Humvees flying large American flags began to appear in and around Manbij to dissuade Turkish-backed militias and other groups from attacking the area. The American troops include a unit of Army Rangers, who appear to have been sent to northern Syria from the base American forces use in Erbil, Iraq. It was an unusually public role for Army Rangers, who often prefer to operate in the shadows.
Capt. Jeff Davis, a Pentagon spokesman, said Monday that the American deployment was intended as a “visible sign of deterrence and reassurance.”
“We are concerned about anybody who views Manbij as needing to be liberated,” he added.
One American official described the situation around Manbij as a potential tinderbox. There have already been a couple of friendly fire incidents, including a Russian airstrike last week that hit Syrian Arab fighters trained by the Americans. The worry is that a small incident could rapidly escalate and undermine the American-backed push to capture Raqqa, the capital of the Islamic State’s self-styled caliphate.
“There is a need for an effective coordination in the efforts to clear Syria of all terror groups because so many countries are involved there,” Binali Yildirim, the Turkish prime minister, said of the generals meeting. “That’s the real aim of the meeting.”
The challenge facing the United States and Turkey, however, goes well beyond drawing clear battle lines.
American Special Operations Forces regard the Y.P.G. — the Syrian Kurdish militia that is officially known as the People’s Protection Units — as an effective battlefield ally whose participation is vital to roll back the Islamic State in Syria.
While President Trump has yet to decide the matter, American commanders have also argued for equipping the Y.P.G. with armored vehicles, heavy machine guns and anti-tank missiles so they could join the operation to seize Raqqa.
Turkey, which has cast the Kurdish militias as terrorists, has vociferously objected to such a move. The American military has tried to develop ways to reassure Turkey, including by increasing the number of Syrian Arabs that would be used to take Raqqa.