The Syrian Observatory for Human Rights, which monitors the war in Syria, said Deir el-Zour province continues to witness tensions following the foiled attack and the USA response, and said there were reports of new mobilization to the area.
Defence Secretary James Mattis said Thursday that the United States (US) is not "getting engaged in the Syrian civil war, China's Xinhua News Agency reported".
Last Wednesday, a US -led coalition with defensive air and artillery strikes against the pro-regime forces in Syria killed an estimated 100 pro-regime soldiers.
Around 20 to 30 rounds from artillery and tanks landed within 500 meters of the Syrian Democratic Forces headquarters before the coalition returned fire with a combination of artillery fire and air strikes.
SDF forces responded with artillery and called in United States air strikes.
More than 100 fighters from the pro-regime side were killed in an unprecedented and large clash the included tanks, artillery and rockets.
Washington has deployed 2,000 soldiers in Syria, mainly special forces, who support the Syrian Democratic Forces (SDF), an Arab-Kurdish coalition fighting the IS.
Regime forces were likely attempting to take an oilfield near Khusham.
Kurdish forces in northern Syria pardoned roughly 400 former members of ISIL in early January, adding some of them to the ranks of a USA -backed group, Russia's ambassador to the United Nations charged Thursday. The US had chosen this town to train local Syrian forces to fight IS. About 100 of the attackers were killed, the official said.
Up to 30 tank and artillery rounds landed within 500 meters of the headquarters with USA and Syrian Democratic Forces, Veale said. Any of the attacking vehicles and personnel who turned around and headed back west were not targeted, the military official said.
"We appreciate the Russian Federation's professionalism and regular communication [with its military units deployed to Syria] via the de-confliction line", he noted.
The U.S. -backed coalition, as CNN reported, described the attack as an act of "self-defense" against an "unprovoked attack" by Syrian President Bashar Assad against a Syrian Democratic Forces headquarters.
According to the Syrian Observatory for Human Rights, which only confirmed 45 dead among pro-regime forces, the initial attack took place near Khasham.