Beirut, Moscow – Under Russian air cover, Syrian regime forces crossed on Monday to the eastern bank of the Euphrates River, which allowed warplanes to land at the military airport of Deir al-Zour ahead of transforming it into a headquarter for Russian operations.

“Syrian regime troops, backed by units of the fourth rank division and Russian Aerospace Forces have reached the eastern bank of the Euphrates River near Deir al-Zour and drove ISIS militants out of a number of villages,” the Russian Defense Ministry said in a statement.

The ministry added that the troops will launch an offensive in the western part of the city to expand their control over the area.

According to the Syrian Observatory for Human Rights, the latest development comes in the framework of the regime forces’ attempts to encircle and besiege Deir al-Zour before advancing on the eastern countryside of the city along the western bank of the river.

Meanwhile, Syria’s state news agency SANA reported that the first two cargo planes landed at Deir al-Zour airport carrying large quantities of supplies for military forces operating in the area after the surroundings of the airport had been fully secured.

By passing the Euphrates River, regime forces were now at a crossing point with US-backed Syrian Democratic Forces (SDF), which are fighting ISIS from the eastern side of the river.

On Monday, the SDF made a quick advance in the area after reaching to within just 6 kilometers of the eastern bank of the river across the city of Deir al-Zour.

Coalition spokesman Colonel Ryan Dillon declined to say whether the Syrian regime forces crossing the river violated the de-confliction line.

“The closer together the Syrian regime and the SDF get, the more awareness is going to be required,” Dillon told AFP.

Mustafa Bali, a spokesperson for the SDF and head of its media center in Ain Issa told Asharq Al-Awsat on Monday that his forces did not document any crossing by Syrian forces to the eastern strip. He also denied the presence of any agreement with the regime on such a move.

“We do not accept this operation, unless it is made in the framework of an agreement, which is not yet present,” he said.