ISTANBUL (WASHINGTON POST) - Russia announced on Tuesday (Oct 15) that its units were patrolling between the Turkish and Syrian militaries near the northern Syrian town of Manbij, in a sign that Moscow, a key ally of the Syrian government, was moving to fill a security vacuum after US troops were withdrawn from the area.

A Russian Defence Ministry statement said that military police in north-western Manbij were patrolling "along the line of contact between the Syrian Arab Republic and Turkey." The statement said the Russian military was also "interacting" with Turkey's government.

A US official said US troops had withdrawn from Manbij. Early Tuesday, Syrian state television reported that government troops had entered the town, airing video footage of what it said were residents celebrating the arrival of Syrian forces in the center of Manbij.

Syrian Arab News Agency, a state media outlet, shared video on Oct 14 showing Syrian troops entering the border town of Tal Tamr after a deal was reached with Kurdish fighters.

The developments come a day after the Syrian Kurds announced that they had struck an agreement with the government of President Bashar Assad aimed at blunting a nearly week-long Turkish government offensive into Kurdish-held territory in northern Syria.

The deal would allow Syrian government forces to take over security in some border areas, according to Syrian Kurdish officials, who said their administration would maintain control of local institutions.

Ankara has said its military operation is aimed at clearing the border of Syrian Kurdish forces with links to Kurdish militants inside of Turkey and repatriating Syrian refugees to the country.

The United States and other western allies of Turkey have condemned the operation, warning it could lead to the resurgence of the Islamic State in Iraq and Syria (ISIS) militant group. The Trump administration on Monday called on Turkish President Recep Tayyip Erdogan to implement an immediate cease-fire and imposed sanctions against Turkey's defence and energy ministries, as well as three senior Turkish officials.

Trump has been harshly criticised, including by some of his own Republican allies, for withdrawing US troops and leaving the US-allied SDF to face the Turkish military. Vice President Pence announced on Monday that he was leading a delegation to Turkey in the "immediate future" in an effort to end the violence.

Erdogan has given no indication he is willing to halt the offensive. "We will soon secure the region from Manbij to the border with Iraq," he said on Tuesday, during a visit to Azerbaijan, referring to a 230-mile expanse.

Turkish-backed forces operating under the Syrian National Army, an umbrella group of rebel factions, had announced on Monday the start of an operation to retake the city of Manbij from the SDF.

Turkey had long demanded that the United States expel the SDF from Manbij and complained that a deal struck with Washington to remove the fighters was not being implemented.

Turkey and the United States agreed in December on a plan for the Kurdish-led SDF to withdraw from Manbij, about 40km west of the Euphrates River, and a road map envisioned joint US-Turkish patrols in the city. Turkish officials view the Kurdish fighters in Syria as terrorists because of their links to the Kurdistan Workers' Party (PKK), which has waged a decades-long war for autonomy inside Turkey.

The Turkish-backed Syrian National Army said on Tuesday that its forces had "started freeing villages" around Manbij a day earlier but had not entered the town.

The battles have taken a withering toll on Syrian civilians. The United Nations has said that as many as 160,000 people, including 70,000 children, have been displaced since the fighting in north-east Syria escalated nearly a week ago. The Kurdish administration said on Tuesday that there as many as 275,000 internally displaced people in the region.

The Kurdish Red Crescent said on Monday that said international aid groups had pulled their international staff from the northeast, leaving camps for displaced people with "extremely limited support."

Mercy Corps, which had been operating in the area since 2014, said on Monday it was suspending operations in north-east Syria and evacuating international staff.

"This is our nightmare scenario," said Made Ferguson, the group's deputy country director for Syria in a statement.

"There are tens of thousands of people on the run and we have no way of getting to them. We've had to pull our international staff out of northeast Syria. We just cannot effectively operate with the heavy shelling, roads closing, and the various and constantly changing armed actors in the areas where we are working."