Military action against Syria over the use of chlorine would represent a de facto shift in policy.
A suspected chlorine attack on Sunday by the Syrian government in northwest Syria is under investigation by the United States, State Department officials say.
Syrian Special Envoy Jim Jeffrey told the House Foreign Affairs Committee on Wednesday that the United States so far could not confirm the specific chemical agent used.
"We at this point do not have any confirmation that chlorine, which was the substance that was suggested or alleged has been used — but again, we haven't finished our review of that,” Jeffrey said.
On Tuesday, State Department spokeswoman Moran Ortagus said that the United States “continues to see signs” that Syrian President Bashar al Assad’s government “may be renewing its use of chemical weapons, including an alleged chlorine attack in northwest Syria.” Ortagus said the Trump administration considers the use of such weapons unacceptable.
President Trump has twice launched limited air strikes on the Syrian regime following chemical weapons attacks in April 2017 and April 2018 that killed more than 120 people.
The acting U.S. representative to the United Nations, Jonathan Cohen, said on Friday that “any use of chemical weapons, including chlorine gas, will be met by a strong, swift response.”
Neither Ortagus nor Jeffrey specified whether that response might include further strikes on the Assad regime.
But past airstrikes have responded to the use of what was believed at the time to be sarin — “the most volatile of the nerve agents,” according to the Centers for Disease Control and Prevention — rather than the less-deadly chlorine. If the United States were to take military action against Syria over a chlorine attack, it would represent a de facto shift in U.S. policy.
“Even though officials have been loath to admit it, the prohibition against chemical weapons use in Syria has in the past been understood to only pertain to highly lethal nerve agents such as sarin but not the easily-produced and far less deadly chlorine,” Tobias Schneider, an independent analyst who tracks reported chlorine attacks, told the Washington Post in 2018.
As an official matter, the State Department considers the use of chlorine gas to violate the Chemical Weapons Convention. In 2013, Assad’s government signed the agreement and subsequently turned over various chemical weapons. But no chlorine was among those relinquished stockpiles, and Syria is believed to have since used chlorine gas as a weapon.
The United States has an uneven history of responding to chemical gas attacks in Syria. President Obama in 2012 famously said that the use of chemical weapons would be a “red line,” but lacking support from Congress, did not act after a suspected sarin attack by Assad the following year. Republicans have since ridiculed Obama for failing to follow through. Trump also said that the use of chemical weapons would be a “red line” before the 2017 and 2018 strikes.
“So far, we cannot confirm it,” Jeffrey said.