Trump suggested Monday he had little doubt that Syrian government forces were to blame for what he said was a chemical attack, but neither he nor other administration officials have produced hard evidence. Officials suggested such evidence was lacking, or at least not yet at hand. This is in contrast to an incident one year ago in which U.S. intelligence agencies had video and other evidence of certain aspects of the actual attack, which involved the use of Sarin gas. Trump responded by launching Navy cruise missiles at a Syrian airfield.