"I think the United States and us and others will do whatever we can to meet this very dangerous weapon," he said. "The sooner the better."
Syria has said it is rebels who have used chemical weapons.
Sarin gas is an odorless nerve agent that can cause convulsions, paralysis and respiratory failure. Nerve agents are the most toxic and rapidly acting of the known chemical warfare agents, according to the Centers for Disease Control and Prevention.
Sarin quickly evaporates from liquid to vapor form to disperse into the environment. It also mixes easily with water and can poison a water supply.