The United States fired 50-70 precision-guided missiles at Syria's Shayrat air base at 8:45 p.m. eastern standard time, focusing on key points in the airfield, including runways, aircraft and fuel points. According to MSNBC, 59 of the missiles hit their targets. This air base reportedly houses the two squadrons of Su-22 ground attack aircraft that carried out the recent chemical weapons attack. Syrian state media responded to the U.S. strikes, called them an act of aggression. The president called on the nations of the world to work to end the conflict and bloodshed in Syria. The United States vetted the target of the strikes to ensure no civilian casualties or Russian personnel were injured, Congressman Adam Schiff said, MSNBC reported. One U.S. defense official said that there were Russians stationed at the air base, but that Washington informed them in advance of the impending strikes. There was a significantly more comprehensive list of military options available to the United States in 2013 following the Eastern Ghouta chemical weapons attack; it had fewer options today in light of the Russian presence.