WASHINGTON — The U.S. has no evidence to confirm reports from aid groups and others that the Syrian government has used the deadly chemical sarin on its citizens, Defense Secretary Jim Mattis said Friday.
"We have other reports from the battlefield from people who claim it's been used," Mattis told reporters at the Pentagon. "We do not have evidence of it."
He said he was not rebutting the reports.
"We're looking for evidence of it, since clearly we are dealing with the Assad regime that has used denial and deceit to hide their outlaw actions," Mattis said.
Syrian President Bashar Assad denies his government has used chemical weapons.
Mattis says it is clear that Assad's government has weaponized and used chlorine gas in the Syrian civil war.
"We're even more concerned about the possibility of sarin use," he said. Sarin is a colorless and tasteless toxin that can cause respiratory failure leading to death.
Last April, the U.S. launched several dozen Tomahawk cruise missiles at a Syrian air base in response to what it called illegal Syrian use of chemical weapons. President Donald Trump said the attack was meant to deter further Syrian use of illegal weapons.
In his remarks Friday, Mattis alluded to the April attack, saying, "So they'd be ill-advised to go back to violating" the international prohibition on the use of chemical weapons.
On Thursday, the Trump administration accused Assad of producing and using "new kinds of weapons" to deliver deadly chemicals. Administration officials said Trump has not ruled out additional military action to deter chemical attacks or to punish Assad, though they did not suggest any action was imminent. They emphasized that the United States was seeking a new way to hold users of chemical weapons accountable and wanted cooperation from Russia, Assad's patron, in pressuring him to end the attacks.