Kerry, one of the leading advocates of a military assault on Assad, claimed the US had identified the type of nerve agent used in the 21 August attacks on 12 neighbourhoods outside Damascus.
In a round of appearances on the Sunday political shows in the US, he said the evidence of sarin came from blood and hair samples from first responders who helped victims of the attacks.
Kerry said the evidence had not come from United Nations weapons inspectors, but did not give any further details of the source for the samples, nor where or when they had been tested. He said the case for attacks against the Syrian regime was growing stronger “by the day”.
The secretary of state stressed that President Obama had the right to take action “no matter what Congress does”.
Assad remains defiant
Meanwhile, even as US secretary of state Kerry made the stronger case against Syria, Damascus hailed an ‘historic American retreat’ on Sunday, mockingly accusing President Obama of hesitation and confusion after he delayed a military strike to consult Congress.
Assad said Syria was capable of confronting any external attack, but left the most withering comments to his official media and a junior minister.
However, Syria’s opposition coalition called on Sunday on US Congress to approve military action and said any intervention should be accompanied with more arms for the rebels.