Russian Foreign Minister Sergey Lavrov said on Wednesday the withdrawal of all non-Syrian forces from Syria's southern border with Israel should happen as soon as possible, the TASS news agency reported.
Rebels control stretches of southwest Syria, bordering the Israeli Golan Heights, while Syrian army troops and allied Iran-backed militias hold nearby territory.
"We have well-known agreements concerning the southwestern de-escalation zone," Lavrov continued. "Those agreements were concluded by Russia, the United States and Jordan. Israel was perfectly aware of them while they were still being drafted. They stipulate that the zone of de-escalation is expected to consolidate stability and that all non-Syrian forces must be pulled out of that area. I believe this must happen as soon as possible. This is precisely what we are busy with now in cooperation with our Jordanian and U.S. counterparts."
On Tuesday, Russia, the United States and Jordan agreed to hold a meeting about the fate of Syria's southern de-escalation zone, Russian Deputy Foreign Minister Mikhail Bogdanov confirmed.
"Contacts are continuing with the Jordanians and the Americans" about this area where different armed groups are located, Bogdanov said. "We support the idea of a trilateral meeting at a level suitable for our partners. The sooner the better."
Washington warned Damascus on Saturday it would take "firm" action if the regime of Bashar Assad violates a cease-fire deal, after Syrian aircraft dropped leaflets on a southern province ahead of an expected offensive.
Lavrov on Monday stated that only Syrian army troops should be on the country's southern border with Jordan and Israel, after Washington warned of "firm measures" over truce violations in the region.
A senior Jordanian official said his country was discussing developments in southern Syria with Washington and Moscow and that all three parties saw "eye to eye" on the need to preserve the de-escalation zone which they brokered last year and which has reduced violence.
"The de-escalation zone has produced the cease-fire that has held best in all of Syria. The parties to the agreement are all committed to preserving it," the official said. "We are closely watching developments and will protect our national security," the official added of the "fluid" situation.
Syrian state media, meanwhile, reported leaflet drops on rebel territory there urging fighters to accept government rule, and a U.K.-based monitor has reported army movements into the south – two signs of a potential military offensive.
Syria's state-run Al-Baath daily said in an editorial published Monday that the U.S. threat underscores the "dirty American role in the terrorist war" against Syria. It stressed that the Syrian army was determined to retake all parts of Syria.
Lebanon-based Al Mayadeen TV, which has reporters embedded with Syrian troops, said the army is sending reinforcements to southern Syria in an apparent preparation for an offensive.