The United States, France, and Britain are warning Syrian President Bashar al-Assad not to use chemical weapons as he launches a campaign to retake the last remaining rebel-held province in Syria.
In a joint statement issued late on August 21, the three Western powers said "we remain resolved to act if the Assad regime uses chemical weapons again" as it embarks on a military offensive in Idlib Province after reasserting control over most other rebel-held areas of the country since last year.
Assad's forces have started heavily bombing and shelling Idlib, which lies next to the border with Turkey and where holdout rebels from all over the country were transported in recent months under Russian-brokered deals offering them safe passage to Idlib if they surrendered territory they once held around Damascus and other areas.
Assad's assaults against major rebel strongholds in the country's seven-year civil war have followed a pattern, with initial heavy bombing and artillery attacks followed by the alleged use of chemical weapons in an apparent attempt to intimidate rebels and force civilians to flee the area under siege.
In light of this pattern, the three Western powers stressed their "concern at the potential for further -- and illegal -- use of chemical weapons."
Britain, France, and the United States said that "our position on the Assad regime's use of chemical weapons is unchanged" since the three powers staged air raids in April to eliminate sites where chemical weapons allegedly were made, in response to an alleged chemical attack that occurred in Douma weeks earlier.
"As we have demonstrated, we will respond appropriately to any further use of chemical weapons by the Syrian regime, which has had such devastating humanitarian consequences for the Syrian population," the three powers said.
Assad has denied using chemical weapons, and efforts by Western powers at the UN to rebuke Syria over alleged chemical attacks have been batted down by Syria's biggest ally, Russia, in recent years.
The impasse at the United Nations is what led the United States, Britain, and France to act on their own earlier this year.
The three allies released their warning to Syria on the anniversary of what they called a "horrific" sarin-gas attack in Ghouta outside Damascus that killed more than 300 people five years ago.
That attack, which the West blamed on Assad's forces, led to a U.S.-Russian agreement to rid Syria of its chemical stockpile and its means to produce the deadly chemicals.
But despite the agreement, numerous chemical attacks have occurred since then, with most of them documented by the global chemical weapons watchdog and blamed on the Syrian government.
The UN Security Council is scheduled to discuss the situation in Syria next week.