Syrian fighter jets flew over the western Daraa countryside in an attempt to pressure opposition factions.
The flyover was the first since the signing of the American-Russian agreement over the region in mid-2018.
The Syrian Observatory for Human Rights confirmed the flyover.
The development took place amid Russian and Syrian regime threats to launch a widescale ground and air operation against western Daraa.
The western Daraa countryside has witnessed a fragile calm after Russian forces gave the Fourth Armored Division, led by president Bashar Assad’s brother Maher, an ultimatum to hand over or expel eight former leaders of factions in Tafas city to northern Syria within 72 hours or face a widescale military operation.
The regime forces and Fourth Armored Division were also ordered to surrender weapons in Tafas to avoid the operation.
In return, the regime demanded that Division be allowed to set up checkpoints around Tafas, carry out raids against suspected ISIS members and take over all government buildings.
The opposition Naba outlet said Russia appeared receptive to the proposal.
The Observatory said locals objected to the ultimatum, rejecting any forced displacement of people and even threatening to attack regime forces if they carry out any operation in the Tafas area.
The war monitor said unknown gunmen attacked a regime checkpoint on the international highway near the town of Saida in the eastern Daraa countryside. Casualties were reported in the ensuing clashes.