Shortly after leaving their Damascus hotel. United Nations inspectors came under sniper fire. No one was injured, and the international team of investigators continued to the site of a suspected chemical attack in the suburbs of the Syrian capital.
Activists say hundreds of civilians were killed five days ago and video shows victims suffering symptoms consistent with exposure to toxic gas.
Speaking from South Korea Senator John McCain said the US can no longer sit on the sidelines.
"If the United States stands by, and doesn't take very serious action, not just launching some cruise missiles, then again, our credibility in the world is diminished even more, if there is any left," said Sen. John McCain, R-AZ.
A senior Obama Administration official says there is little doubt Syrian President Bashir Assad's regime launched a chemical weapons attack. Now the White House is moving toward a military strike against Syria.
"The United States is looking at all options regarding the situation in Syria," said Secretary of Defense Chuck Hagel.
The U.S. is talking to European allies about the scale of the military response.
"There's no question, the administration is building support among NATO allies. Our assets are in place, I don't think there is any question in the administration's mind that chemical warfare has been used," said Sen. John Corker, R-TN.
Monday Syrian leader Assad told Russian journalists he has never used chemical weapons, and warned the US against getting involved.
In a recent survey, only 25-percent of Americans say the U.S. should get involved even if chemical weapons have been used.