WASHINGTON - US Secretary of State John Kerry said Sunday Washington has proof the Syrian regime used sarin gas in a deadly attack, as he sought to overcome deep skepticism in Congress over military strikes.
The top US diplomat warned the world cannot turn a blind eye to chemical weapons, as he urged lawmakers to support President Barack Obama's call for limited military action.
Hair and blood samples from the emergency workers who rushed to the scene of last month's attack in Damascus given independently to the United States have shown signs of the powerful sarin nerve gas, Kerry told US television channels.
"In the last 24 hours, we have learned through samples that were provided to the United States and that have now been tested from first responders in East Damascus, (that) hair samples and blood samples have tested positive for signatures of sarin," Kerry told NBC's Meet the Press.
He blitzed the Sunday morning talk shows, upping the ante in the Obama administration's push to build the case for US military strikes against the regime of President Bashar al-Assad.
But after an emergency classifed briefing on Sunday at the US Capitol, many US lawmakers still appeared unconvinced.
Obama, who later this week attends a G20 summit in Russia where Syria is likely to top the agenda, took a huge political risk in handing the decision to deeply-divided lawmakers - especially after the British parliament voted against any military involvement.
"There's no support for the resolution as it is," said House Democrat Jim Himes after the briefing in reference to the White House's formal request for authorisation to conduct strikes.