ANKARA, Turkey — Syrian Kurdish forces have started withdrawing east of the Euphrates River, Turkish officials said Thursday, a move that could fulfill a major demand by Ankara and the United States a day after Turkey sent in tanks across the border to help Syrian rebels take a key Islamic State stronghold.
The Turkish officials were quoting U.S. Secretary of State John Kerry, who relayed the news in a telephone conversation with his Turkish counterpart.
Turkey's surprise incursion Wednesday to capture the town of Jarablus was a dramatic escalation of Turkey's role in Syria's war. But Ankara's objective went beyond fighting extremists. Turkey is also aiming to contain the expansion by Syria's Kurds, who are also backed by the United States and have used the fight against IS and the chaos of Syria's civil war to seize nearly the entire stretch of the border with Turkey in northern Syria.
U.S. Vice President Joe Biden flew into Ankara hours after the offensive was launched, and he backed Turkey with a stern warning to the Kurds to stay east of the Euphrates, which crosses from Turkey into Syria at Jarablus.
Kurdish forces "must move back across the Euphrates River. They cannot, will not, under any circumstance get American support if they do not keep that commitment," Biden said.
According to Turkish ministry officials, Kerry and Mevlut Cavusoglu discussed the Turkish military operation.
Kerry stressed that the Syrian Kurdish forces "were in the process of retreating east of the Euphrates," the officials said, speaking on condition of anonymity in line with government regulations
It was unclear Thursday whether Turkey-backed rebels who seized Jarablus Wednesday would move against IS-held towns of nearby Kurdish-controlled areas, including the town of Manbij, which Kurdish forces retook from IS earlier this month. Manbij lies west of the Eurphrates and Ankara has demanded the Kurds hand it over to Syrian rebels and withdraw.
On Thursday, Turkish forces were securing the area around Jarablus, Turkey's Defense Minister Fikri Isik said. He said the Turkish-backed operation has two main goals — to secure the Turkish border area and to make sure the Kurdish Syrian forces "are not there."
"It's our right to remain there until" the Syrian opposition forces take control of the area, Isik said.
Turkey is concerned about the advances of the Kurdish Syrian forces, fearing they aim to set up a Kurdish entity along Turkey's border with Syria. Ankara maintains that the Syrian Kurdish militia is linked to Kurdish rebels waging an insurgency in southeastern Turkey.
Isik says Ankara and the United States have agreed the Kurdish Syrian forces would pull out of the northern area around Jarablus "within two weeks." Speaking to the private NTV television, he said that "for now, the withdrawal hasn't fully taken place. We are waiting for it and following it."
Kurdish officials contacted by The Associated Press would not confirm or deny that their forces are withdrawing east of the Euphrates River.
Instead, the main Syrian Kurdish faction, known as the YPG, said its troops have "returned to their bases" after helping liberate Manbij from the Islamic State group.
That statement refers to an apparently separate pullout from the withdrawal that Turkey is seeking from the Kurdish forces. The Kurdish forces' statement said they handed control of the northern Syrian city to a newly-established Manbij Military Council, made up of rebel fighters from the town.
The council's spokesman, Sherfan Darwish, earlier said the Syrian Kurdish YPG contingent that helped liberate Manbij earlier this month numbered about 500 fighters.
Turkey has been deeply concerned by the advances of the Kurdish forces, fearing they aim to set up a Kurdish entity there. Ankara maintains that the Syrian Kurdish militia is linked to Kurdish rebels waging an insurgency in southeastern Turkey.
On Thursday, at least 10 more Turkish tanks were seen crossing into Syria at the Turkish border town of Karkamis, the private Dogan news agency reported.
The Turkish assault, launched in retaliation after a string of militant bombings in Turkey, adds yet another powerhouse force on the ground in an already complicated war.
A senior Turkish official told reporters that operations would continue until "we are convinced" that imminent threats to Turkey are neutralized. He said the aim is to create a "terror-free zone" in northern Syria to prevent militants from entering Turkey. The official also spoke on condition of anonymity in line with government regulations.
Meanwhile, Syria's foreign minister arrived in Baghdad on a previously unscheduled visit, the first in more than three years. The Iraqi foreign ministry announced his arrival but provided no further details.
The last time Syria's foreign minister visited Baghdad was in 2013, before the Islamic State group pushed into Iraq from neighboring Syria overrunning large swaths of territory in the country's north and west.
Associated Press Writers Philip Issa in Beirut and Susannah George in Baghdad contributed to this report.