A displaced Syrian family unload their belongings at a makeshift camp for displaced people near the town of Manbij, Syria. (Delil Souleiman/Agence France-Presse via Getty Images)

Turkey has ordered Oregon-based Mercy Corps, one of the largest humanitarian organizations delivering aid to Syria, to immediately shut down its Turkish operations, ending a program that provides regular assistance to hundreds of thousands of besieged Syrian civilians and refugees.

“Our hearts are broken by this turn of events, which comes after five years of cooperation with the government of Turkey and other partners,” spokeswoman Christine Bragale said in a statement early Wednesday.

It was unclear whether other aid organizations have been similarly affected, and Turkish government officials could not immediately be reached for comment. Bragale said that no specific reason had been given and that “we continue to seek a dialogue with Turkish authorities” and “remain hopeful that the government of Turkey will allow us to return to serve those in critical need.”

Turkey has admitted more than 3 million refugees fleeing violence in Syria, and towns and cities along its southern border have been a hub for sending humanitarian supplies into the war-torn country.

Mark Toner, acting spokesman for the State Department, said it was aware of the situation with Mercy Corps, which he called a “valuable partner” in delivering humanitarian assistance to needy Syrian refugees. “We have informed the government of Turkey of our concerns regarding Mercy Corps’ closure and the impact it will have

on their ability to provide critical humanitarian assistance to vulnerable populations,” he said.

Mercy Corps’ expulsion is likely to increase growing tension along Syria’s northwest border, where the myriad military forces involved in a civil war and the separate fight against the Islamic State have converged in pursuit of conflicting objectives.

[U.S. military aid is fueling big ambitions for Syria’s leftist Kurdish militia]

Turkish forces, along with Syrian rebel allies, crossed the border last fall to clear part of the area of Islamic State fighters. The larger Turkish goal has been to prevent U.S.-backed ­Syrian Kurds, whom Turkey considers terrorists, from expanding their control over the border region.

Turkey has said it wants to create a safe zone inside Syria along the border, 60 miles long and about 28 miles deep. But that area would include the town of Manbij, taken from the Islamic State last summer, with U.S. assistance, by the joint Kurdish and Arab Syrian Democratic Forces, or SDF.

The U.S. military hopes to use the SDF, bolstered with recruits, to capture the city of Raqqa, the Islamic State’s Syrian capital, in an offensive planned for this year. Turkey has objected, and its force is headed toward Manbij. To head them off, Russian and Syrian government troops have moved into villages west of the town, and U.S. Special Forces arrived in Manbij last weekend.

The growing controversy brought together the top military officials from Turkey, the United States and Russia on Tuesday in the Turkish city of Antalya, a new step in exploring how military operations by the three countries will occur in increasingly tight quarters in Syria.

The meeting between Marine Gen. Joseph F. Dunford Jr., chairman of the Joint Chiefs of Staff; Russian Gen. Valery Gerasimov; and Turkish Gen. Hulusi Akar was at Turkey’s invitation.

It marked the second meeting in a month between Dunford and Gerasimov, as senior U.S. military officials have called for increased talks to “deconflict” operations in Syria and make sure there are no collisions between U.S. and Russian aircraft.

[Pentagon plan to seize Raqqa calls for significant increase in U.S. participation]

Under a framework established in 2015, a U.S. colonel in Qatar and a Russian counterpart in Syria discuss the locations of operations their countries are carrying out in Syria without sharing intelligence. Russia has pushed to expand collaboration in Syria, something that President Trump has said he would favor in the fight against the Islamic State.

Even as they vie for Turkey’s support, both the United States and Russia have cooperated with the Syrian Kurdish People’s Protection Units, or YPG. Turkey has labeled the YPG an affiliate of the separatist Turkish Kurdistan Workers’ party, which Washington and Ankara have designated a terrorist group.

In a statement, the Joint Chiefs of Staff said the three generals gathered to discuss “regional security matters in Syria and Iraq, specifically the current situation of the fight against all terrorist organizations in Syria, with an effort to wage a more effective fight against all terrorist organizations in the future and the importance of additional measures for de-conflicting operations.”

Turkish Prime Minister Binali Yildirim told a news conference that more coordination among the three is needed.

Carol Morello in Washington and Liz Sly in Beirut contributed to this report.

Correction: An earlier version of this article incorrectly said that the Russian government had designated the Turkish Kurdistan Workers’ Party a terrorist group. The article has been corrected.

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