"If we fail to act, we're going to have fewer allies. We are going to have fewer people that count on us, certainly in the region," Secretary of State John Kerry told the US Senate.
Kerry, who has spent hours talking to world leaders over phone after the alleged chemical attack in Syria on August 21 that killed more than 1,400 people, yesterday said that the credibility of US is at stake.
"It's fair to say that our interests would be seriously set back in many respects if we are viewed as not capable, or willing to follow through on the things that we say matter to us," the Secretary of State said.
Describing the use of chemical weapons a violation of the world's "red line", Kerry said that no action by the US would set a dangerous precedent.
"We would be opening Pandora's box with respect to a whole set of dangerous consequences as a result of the United States not keeping its word. And it would make our life very, very difficult with respect to North Korea and Iran," he said.
Congressional debate on President Barack Obama's request for authorisation to strike Syria intensified as Kerry, Defence Secretary Chuck Hagel and General Martin Dempsey, Chairman of the Joint Chief of Staff, briefed the lawmakers on the Senate Foreign Relations Committee.
"A refusal to act would undermine the credibility of America's other security commitments, including the president's commitment to prevent Iran from acquiring a nuclear weapon. The word of the United States must mean something. It is vital currency in foreign relations and international and allied commitments," Hagel told lawmakers at a Senate hearing on Syria.