Syrian regime forces on Saturday made their first gains on the ground against rebel fighters in the southern province of Daraa after several days of intensified bombardment, a monitor said.
Since Tuesday, regime troops have been ramping up their bombardment of opposition-held areas in Daraa's eastern countryside ahead of an expected military offensive against rebels there.
"Regime troops made their first advance in the area since the military escalation on Tuesday, seizing the villages of Al-Bustan and Al-Shumariya in the eastern part of Daraa province," said the Britain-based Syrian Observatory for Human Rights.
The fighting is currently focused on a wedge of rebel territory between Daraa's eastern countryside and the western part of the neighbouring province of Sweida.
The army appears to want to split that wedge into a northern and southern section, Observatory head Rami Abdel Rahman said, "to facilitate their operations and increase the pressure on rebel factions, allowing it to advance more quickly".
Syrian state news agency SANA also reported the advance, saying army units had edged forward against rebels in Daraa's east.
It also reported rebel mortar fire killing two civilians, including a child, in government-held parts of Daraa city.
Since retaking rebel strongholds around the capital Damascus in recent months, Syrian regime forces have turned to the country's south, where opposition forces still hold a majority of the provinces of Daraa and Sweida.
Southern Syria is a strategically vital zone: it borders both Jordan and the Israeli-occupied Golan Heights, and also lies close to Damascus.
Military reinforcements have been streaming into the south despite its designation last year as a "de-escalation zone".
The Observatory has noted an "ongoing escalation of shelling and clashes in eastern and northeastern parts of Daraa province".
The regime has used air strikes and artillery and has even resumed dropping its notorious barrel bombs on Daraa province.
The crude devices slammed onto the town of Al-Herak on Friday in the first use of the weapon on Daraa in nearly a year, according to the Observatory.
The escalation has left at least 19 civilians dead across rebel areas since Tuesday, it said.
At least eight regime troops were also killed in clashes with rebels on Saturday, the Observatory said, bringing to 13 the total number of government loyalists killed since the escalation.
Some 12,000 people have been displaced from Daraa province in recent days, the Observatory said.
The United Nations has also warned that growing violence is putting the lives of 750,000 people in rebel parts of the south in danger.
Even as the regime hints at a looming assault, international powers are holding talks aimed at reaching a negotiated settlement for Syria's south.
A woman walks past a destroyed car in Al-Hirak in Daraa province in southern Syria on June 21, 2018