US 'has evidence of Syrian sarin use'
1 September 2013 Last updated at 15:00 BST
The US has evidence that the nerve agent sarin has been used by the Syrian government, Secretary of State John Kerry says.
Mr Kerry also said he was confident Congress would approve strikes against the forces of Syrian President Bashar al-Assad.
President Barack Obama has delayed any action pending a vote in Congress.
Speaking with ABC news on Sunday, Mr Kerry said: "We have signatures of Sarin in hair and blood samples, so the case is growing stronger by the day."
He added: "We cannot allow Assad to be able to gas people with impunity."