ST. PETERSBURG, Russia -- President Barack Obama, facing hardened international opposition to a strike against Syria and returning home to a skeptical American public, will address the country Tuesday to make his case.
Obama made the announcement Friday at a press conference before leaving a summit of the Group of 20 world powers in Russia. He said that Syria's use of chemical weapons "isn't just a Syrian tragedy. It's a threat to global peace and security."
Obama cast military action in Syria as critical to upholding the world's prohibition on chemical weapons.
"I want people to understand that gassing innocent people, delivering chemical weapons against children, is not something we do," the President said. "It's prohibited in active wars between countries. We certainly don't do it against kids."
The United States says that Assad, more than two years into a civil war, gassed 1,400 people to death, including more than 400 children, in a rebel-controlled neighborhood Aug. 21.
"Obviously, my preference would be against to act internationally, in a serious way, and to make sure that Mr. Assad gets the message," Obama said. "I'm not itching for military action."
Obama said that he would tell Congress and the public in coming days that any American strike would be "limited and proportionate." He did not directly answer a question about whether he would go forward with an attack without the approval of Congress.
Military officials on Friday told NBC News that the White House asked the Pentagon for an expanded list of potential targets in Syria, and one senior official warned that it could represent "mission creep." Asked about the report in St. Petersburg, Obama called it "inaccurate" and declined to elaborate.
The G-20 gathering was meant to focus on economic matters but overshadowed by the crisis in Syria. Obama said that most leaders agreed with him that Assad launched a chemical attack but were divided about whether to respond with force.
As the summit concluded, the Turkish prime minister said "almost all" the leaders there agreed on the need for some action against Syria. And the French president said he backed Obama's call for an American-led strike.
But there were no signs of any broad consensus. Obama met with Russian President Vladimir Putin, an Assad ally, for 20 minutes on Friday, but Putin said their positions had come no closer.
"We understood each other, we listened to each other," Putin said. "We didn't agree with each other's arguments, but we could hear them. We tried to find an agreement towards a peaceful settlement of this crisis."
The Italian prime minister suggested that Obama's pitch had failed to break the deadlock over the issue, posting on Twitter after dinner that "the divisions about Syria were confirmed." And China repeated its opposition.
"A political solution is the only right way out for the Syrian crisis, and a military strike cannot solve the problem from the root," Chinese leader Xi Jinping said, according to state news. "We expect certain countries to have a second thought before action."
Ben Rhodes, a White House spokesman, said as the summit concluded that Obama never expected consensus "if Russia, for instance, is at the table." He said that the goal was still to get the most nations possible behind a response.
"We believe that there are a majority of countries here who understand the importance of the issue, understand who is accountable for the use of chemical weapons, and appreciate that there needs to be international response," he said.
In Washington on Friday, U.S. Ambassador to the United Nations Samantha Power said that Assad had barely dented his stockpile of chemical weapons.
"We assess that although Assad used more chemical weapons on Aug. 21 than he had before, he has barely put a dent in his
enormous stockpile,'' she said at the Center for American Progress think tank in Washington.
"We have exhausted the alternatives'' to military action, she said, adding that Assad must have weighed the fact that Russia would back him in the controversy over his alleged use of chemical weapons and it was naive to think Russia would change its stance.
Obama returns to face a deeply skeptical public and an uncertain future for any vote by the full houses of Congress on authorization of military action. The Senate Foreign Relations Committee narrowly passed authorization earlier this week.
Both liberal Democrats and conservative Republicans have come out against intervention, and polls show that the American public has strong reservations about further U.S. involvement in the Middle East.
"I knew this was gonna be a heavy lift," Obama said in St. Petersburg. "For the American people, who have been through over a decade of war now, with enormous sacrifice in blood and treasure, any hint of further military entanglements in the Middle East are gonna be viewed with suspicion."
Sen. John McCain, R-Ariz., who was one of the yes votes in the Foreign Relations Committee, faced hostile questions from constituents at a town hall-style meeting on Thursday.
Sen. Harry Reid, majority leader in the Democratic-controlled Senate, told reporters he believed a resolution to strike Syria would get 60 votes - the necessary number to overcome a filibuster - but said it was "a work in progress." He invoked the gassing of tens of thousands during World War I, the catalyst for world opposition to chemical weapons.
"That's why the international community, rarely agreed on anything, but they agreed that this was wrong," he said. "If this doesn't call for a response, I don't know what does."
The United States has essentially given up on winning approval for a strike from the United Nations Security Council, where China and Russia are permanent members and each hold veto power.
Meanwhile, the State Department withdrew all non-emergency Embassy workers and their families from Beirut, Lebanon, a step it said it was taking "given the current situation in Syria" and potential threats to American interests.
The State Department also gave Embassy workers in part of Turkey the option to leave. The department issued a warning on Thursday against all non-essential travel by U.S. citizens to Iraq because of concern about kidnapping and terrorist violence.