"There have been a number of these attacks. In many cases, you know we don't have troops, we're not engaged on the ground there, so I cannot tell you that we had evidence, even though we had a lot of media and social media indicators that either chlorine or sarin were used," Mattis said, speaking to members of the House Armed Services Committee on Thursday.
The defense secretary said he did believe that a chemical attack took place, but that the US was still "looking for the actual evidence."
"We're still assessing the intelligence, ourselves and our allies. We're still working on this," he reiterated.
"On a strategic level, [the issue is] how do we keep this from escalating out of control, if you get my drift on that," he said, alluding to the prospects of a confrontation between Russian and US forces deployed in the Middle Eastern country.
No Decision Yet
According to Secretary Mattis, President Trump has yet to decide whether or not to launch an attack. "We've not yet made any decision to launch military attacks into Syria," he said.
"I don't want to talk about a specific attack that is not yet in the offing, knowing that this would be pre-decisional. Again, the president has not made that decision," he added.
No Congressional Approval Needed
Asked if the US was ready to mount an attack, Mattis replied that "We stand ready to provide military options if they're appropriate, as the president determined."
Emphasizing that the use of chemical weapons was "simply inexcusable," the defense secretary also accused Moscow of complicity in Syria's alleged retention of a chemical weapons stockpile.
Syrian opposition media reports last week of an alleged chemical attack by government troops prompted the US and its allies to blame Damascus and to start preparations for a possible military response. The Syrian government denied responsibility. The Russian Center for Reconciliation sent inspectors to Douma, finding no trace of chemical weapons use. Moscow has called for an independent investigation into the matter.
Syria destroyed its chemical weapons stockpile in 2013 in a deal brokered by Russia and the United States in exchange for the latter's agreement not to attack the Middle Eastern country. In 2014, the Organization for the Prohibition of Chemical Weapons confirmed that Syria's chemical weaposn arsenal had been eliminated.
