A key U.S. Senate panel has voted in favor of a possible military strike against Syria.
The Foreign Relations Committee voted 10 to 7 Wednesday to give President Barack Obama the authority to take military action against Syria over its use of chemical weapons on civilians.
The Senate resolution calls for limited action lasting no more than 90 days and says no U.S. soldiers would be put on the ground.
The measure will now go to the full Senate. The House of Representatives must also vote on the measure.
Before the vote, Mr. Obama said in Stockholm that the international community's credibility that is at stake if Syria's chemical attacks are not addressed.
The president said he did not set a "red line" in Syria but that the world did when it outlawed poison gas after World War One.
"I do think we have to act because if we do not, we are effectively saying that even though we may condemn it and issue resolutions and so forth and so on, somebody who is not shamed by resolutions can continue to act with impunity. And, those international norms begin to erode and other despots and authoritarian regimes can start looking and saying 'that's something we can get away with."
Mr. Obama is on a one-day visit to Stockholm before flying to Russia for the G20 summit in St. Petersburg, where Syria is expected to be high on the agenda.
Russian President Vladimir Putin has made comments on Syria that could raise tensions before he hosts Mr. Obama and other G20 leaders.
Mr. Putin, on Wednesday, said U.S. Secretary of State John Kerry was "lying" when he said the Syrian opposition had not become more infiltrated by al-Qaida.
The Russian president also said the U.S. Congress would be sanctioning "aggression" if it approved a U.S. force against Syria, without the support of the U.N. Security Council.
Earlier Wednesday, Mr. Putin said he had not ruled out supporting a U.N. authorization of military force against Syria if there is proof government forces used chemical weapons against civilians.
He told the Associated Press and Russian television that the United States should present "convincing" evidence to the U.N.
In another development, a key U.S. Senate committee could vote as early as Wednesday on a measure authorizing U.S. military force. Leaders of the Foreign Relations Committee agreed late Tuesday on details of the plan that would give Mr. Obama authority to order limited strikes against Syrian military targets.
The resolution must clear the committee and gain approval in the full Senate and House of Representatives before taking effect.
France also says it has evidence Syrian forces were responsible for the deadly attack near Damascus last month. The country's parliament is debating a possible military response in a session Wednesday, though French President Francois Hollande does not need lawmakers' approval to act.
Syria has denied using chemical weapons, alleging it was the rebels who deployed them.