The United States on Thursday blacklisted 18 senior Syrian regime officials, who it said were connected to the country's weapons of mass destruction program, after an international investigation found that regime leader Bashar al Assad's forces were responsible for chlorine gas attacks against civilians.
The action marked the first time the United States has sanctioned Syrian forces officials for the regime's use of chemical weapons, according to a Treasury Department statement.
A joint inquiry by the United Nations and the Organisation for the Prohibition of Chemical Weapons (OPCW) found that Syrian regime forces were responsible for three chlorine gas attacks and that Daesh had used mustard gas, according to reports.
Chlorine's use as a weapon is banned under the Chemical Weapons Convention, which Syria joined in 2013. If inhaled, chlorine gas turns into hydrochloric acid in the lungs and can kill by burning lungs and drowning victims in the resulting body fluids.
Syrian President Bashar al-Assad's regime has denied its forces have used chemical weapons.
"We condemn in the strongest possible terms the Syrian regime's use of chemical weapons," Ned Price, a White House National Security Council spokesman, said in a statement. "The Assad regime's barbaric continued attacks demonstrate its willingness to defy basic standards of human decency, its international obligations, and longstanding global norms."
Following the reports of the international inquiry, Britain and France circulated a draft resolution to the UN Security Council in December that would ban the sale or supply of helicopters to the Syrian regime and blacklist 11 Syrian forces commanders and intelligence officials over chemical weapons attacks during the nearly six-year war.
A vote on the draft resolution has not yet been set, but diplomats said Syrian ally Russia, one of five council veto powers, has made clear it opposed the measures.
Ten of the individuals sanctioned by the United States on Thursday are listed for designation in the draft resolution, which – if adopted – would subject them to a global travel ban and asset freeze.
Russian UN Ambassador Vitaly Churkin said in November that there was "just not enough material proof to do anything" and described the French and British bid to impose UN sanctions as a "misplaced effort."
The Syrian regime agreed to destroy its chemical weapons in 2013 under a deal brokered by Moscow and Washington.
The Security Council backed that deal with a resolution that said in the event of non-compliance, "including unauthorised transfer of chemical weapons, or any use of chemical weapons by anyone" in Syria, it would impose measures that could include sanctions.