President Barack Obama challenged Congress and the international community to respond forcefully to the use of chemical weapons in Syria, saying their credibility and that of the United States is at stake if the attack goes unpunished.
"I didn't set a red line, the world set a red line," said Mr. Obama, referring to nearly a century of revulsion and international pacts outlawing poison gas after nearly 100,000 were killed by chemical weapons during the First World War.
He spoke in Sweden on a one-day visit before heading to St. Petersburg, Russia, where he will join Prime Minister Stephen Harper and other G20 leaders on Thursday.
The situation in Syria seems certain to dominate conversations among leaders, if not the formal agenda of the summit, as Mr. Obama presses his case that the Syrian government is responsible for a chemical attack on civilians outside Damascus last month.
Only France has yet answered Mr. Obama's bugle call for military action, most likely missile strikes, against Syria.
But Canada, while saying it would not participate in any strike, has offered firm support for what Foreign Minister John Baird called the need for a "moral response."
In Washington, meanwhile, a divided Senate Foreign Relations Committee voted 10-7 to back the President's call for military action. But the resolution, which moves to the full Senate for debate, would strictly curb Mr. Obama's room for military manoeuvre. A mix of Republicans and Democrats on the committee took stands for and against, starkly underscoring the deep splits in Congress over how to respond to last month's attack.
Before he left Ottawa for Russia, Mr. Harper spoke with British Prime Minister David Cameron about the humanitarian situation in Syria and neighbouring countries that are hosting some two million refugees, according to a government official. Canada has pledged millions in humanitarian aid to Syria, and with Britain now on the sidelines of a military mission, after Mr. Cameron failed to win support in Parliament for condemning Syria, it is possible a joint effort could take shape now.
Mr. Harper has said he is a "reluctant convert" to supporting a military strike, and that there are no plans at the moment for involvement by the Canadian military.
But Mr. Baird – who was a late addition to the trip, joining Mr. Harper and Finance Minister Jim Flaherty – had strong words for Russian President Vladimir Putin, who has continued to support Syrian President Bashar al-Assad. Mr. Putin has said he opposed any military action outside a mandate from the United Nations Security Council.
"You know, the Russian government's moral, political, material support to Assad has given him the ability to soldier on," he told reporters. The "great issue we're tackling," he added, " [is] Russia's intractability to work with others on this issue."
For Mr. Obama, who came to office on an anti-war platform and collected the Nobel Peace Prize the same year he reached the Oval Office, the role of leading hawk in any crisis is unfamiliar.
Even as he squarely blamed the Syrian government for the use of poison gas against its citizens and urged others to rally behind military action, Mr. Obama denied his presidency's credibility was in play.
"My credibility is not on the line," he said. "The international community's credibility is on the line. And America's and Congress's credibility is on the line."
In Washington, deep splits emerged in Congress with hawks like Republican Senator John McCain objecting to any resolution that too narrowly limited the use of force, while others opposed any military action at all. Mr. McCain voted for the resolution, along with seven Democrats and two other Republicans.
In both Houses of Congress, members were torn. Some like Democratic Illinois Senator Dick Durbin publicly worried about mission creep, saying he had backed military action in Afghanistan in 2001 but never expected that conflict would remain ongoing more than a decade later.
To address such concerns, the Senate resolution authorizing the use of force included a 60-day time limit with a 30-day extension and explicitly prohibited any U.S. combat troops on Syrian territory. It also included a provision demanded by Mr. McCain that the U.S. policy aim was to "change the momentum on the battlefield," which, in recent months, has been held by the Assad regime.
Mr. Obama needs 60 votes for a filibuster-proof passage in the Democrat-dominated 100-seat Senate and 217 in the 435-seat House of Representatives where Republicans have a majority and two seats are currently vacant.