The United States says it will take firm and appropriate measures in response to Syrian government violations in a designated de-escalation zone, southwest of the country.

The US State Department gave this indication after President Bashar Al-Assad said his government would use military force against the rebel-held southwest, if political solution failed.

After seven years of the Syrian conflict, the southwest of Syria, bordering Jordan and the Israeli-occupied Golan Heights, is one of the parts of the country that are still outside the state’s control.

Experts have investigated reported use of chemical weapons by Assad’s government, with more than five hundred thousand people killed in the fighting so far.