Quoting
NYTimes
Even without the evidence that the inspectors are collecting, the United States and other Western powers have concluded that the Aug. 21 attack, which killed hundreds of people, was caused by banned chemical munitions and that Mr. Assad’s forces were responsible, crossing a threshold that required a forceful response.
Chuck Hagel, the United States secretary of defense, said in an interview with the BBC that American forces had “moved assets in place to be able to fulfill and comply with whatever option the president wishes to take.” Asked how soon these forces could be ready, Mr. Hagel said, “We are ready to go.”