Chemical weapons activity seen at Syrian air base 'active preparations for chemical weapons use'

Latest: The US has seen chemical weapons activity at a Syrian air base used for a sarin gas attack in April, the Pentagon said.

Update 5:33pm: The US has seen chemical weapons activity at a Syrian air base used for a sarin gas attack in April, the Pentagon said.

Captain Jeff Davis, a Pentagon spokesman, said the activity at the Shayrat air base indicates "active preparations for chemical weapons use".