The US warning comes following Syrian regime's attack on a de-escalation zone in northeastern Syria held by US-backed Syrian Democratic Forces.
The United States warned Syria on Friday it would take “firm and appropriate measures” in response to ceasefire violations, saying it was concerned about reports of an impending military operation in a de-escalation zone in the country’s southwest.
Washington also cautioned Syrian regime leader Bashar al Assad against broadening the conflict.
“As a guarantor of this de-escalation area with Russia and Jordan, the United States will take firm and appropriate measures in response to Assad regime violations,” State Department spokeswoman Heather Nauert said in a statement late on Friday.
A war monitor, the Britain-based Syrian Observatory for Human Rights, reported on Wednesday that Syrian regime forces fresh from their victory this week against a Daesh pocket in south Damascus were moving into the southern province of Daraa.
TRT World's Oubai Shahbandar has more details from Gaziantep on the Turkish-Syrian border.
Syrian regime-run media have reported that regime's aircraft have dropped leaflets on rebel-held areas in Daraa urging fighters to disarm.
The US warning comes weeks after a similar attack on a de-escalation zone in northeastern Syria held by US-backed Syrian Democratic Forces that mostly comprises of YPG militants — the Syrian offshoot of the PKK terror organisation.
US ground and air forces repelled the more than four-hour attack, killing perhaps as many as 300 pro-Assad militia members, many of them Russian mercenaries.
Backed by Russian warplanes, ground forces from Iran and allied militia, including Lebanon’s Hezbollah, have helped Assad drive rebels from Syria’s biggest cities, putting him in an unassailable military position.
They have recaptured all remaining insurgent areas near Damascus in recent weeks, including the densely populated eastern Ghouta area, as well as big enclaves in central Syria.
Anti-Assad opposition fighters still control two large contiguous areas of territory in the northwest and southwest.
The regime’s gains have brought it to a point where any new military campaign risks putting it in conflict with foreign powers.