Obama Concedes ‘Hard Sell’ at G-20 on Syria Strike

President Obama ran into an impasse in his bid to rally international backing for a military strike on Syria as world leaders wrapped up a summit meeting here Friday deeply divided over the right response to what the Americans have called the deadliest nerve gas attack in decades.

After a dinner debate that lasted into the early morning hours, Mr. Obama emerged with a few supporters but no consensus as other leaders urged him not to attack without United Nations permission, which is not forthcoming. Instead, the president had to resign himself to generalized statements of concern over the use of chemical weapons.

The failure to forge a stronger coalition here in the face of opposition from the Russian host, President Vladimir V. Putin, raised the risks even further for Mr. Obama as he headed home to lobby Congress to give him the backing his international peers would not. It also left Mr. Obama in an awkward position of defending his right to take action largely alone if necessary after campaigning against what he cast as unilateralist foreign policy of his predecessor, George W. Bush.

Mr. Obama acknowledged that he had a “hard sell” with Congress and announced that he would deliver a televised address to the nation from the White House on Tuesday evening.

“Failing to respond to this breach of this international norm would send a signal to rogue nations, authoritarian regimes and terrorist organizations that they can use W.M.D. and not pay a consequence,” he told a news conference, using initials for weapons of mass destruction. “And that’s not a world we want to live in.”

But much of the world, at least as represented at the Group of 20 meeting here in this St. Petersburg suburb, did not favor Mr. Obama’s proposed course of action. Mr. Putin said a majority of the leaders joined him in opposing a military strike independent of the United Nations, including those from China, India, Indonesia, Argentina, Brazil, Italy, Germany and South Africa.

The only countries that supported Mr. Obama’s plan, the Russian leader said, were France, Canada, Turkey and Saudi Arabia, all nations that were on his side when he arrived here on Thursday.

Trying to counter the impression of isolation, the White House arranged for a joint statement including those allies as well as Australia, Italy, Japan, South Korea, Spain and Britain condemning the Aug. 21 attack in the Damascus suburbs that according to American intelligence agencies killed more than 1,400 people through the use of chemical munitions.

“We call for a strong international response to this grave violation of the world’s rules and conscience that will send a clear message that this kind of atrocity can never be repeated,” the statement said. “Those who perpetrated these crimes must be held accountable.” Still, the statement did not explicitly endorse military action.

Speaking with reporters as he was about to end his three-day overseas trip, Mr. Obama repeatedly refused to say whether he would abide by the congressional vote he asked for authorizing the use of force against Syria if lawmakers say no.

“You’re not getting any direct response,” he said. But Antony Blinken, his principal deputy national security adviser, told NPR that while the president maintains he has the authority to act regardless of Congress, “it’s neither his desire nor his intention to use that authority absent Congress backing him.”

The Syria dispute came to dominate the G-20 meeting here and underscored the difficulty Mr. Obama has faced with Mr. Putin in recent months. After Russia gave temporary asylum to Edward J. Snowden, the National Security Agency contractor who disclosed secret American surveillance programs, Mr. Obama canceled a separate one-on-one meeting with Mr. Putin in Moscow.

But the two ended up talking on the sideline of the group session on Friday, mainly about their disagreement over Syria. Mr. Obama said Mr. Snowden’s case did not really come up. “It was a candid and constructive conversation, which characterizes my relationship with him,” Mr. Obama said.

The president said he appreciated that Mr. Putin had allowed a full airing of views about Syria at a long dinner of the leaders Thursday night that stretched on until almost 2 Friday morning. By several accounts, it was a vigorous discussion in which Mr. Obama and Mr. Putin in effect were competing for support. Mr. Obama emerged having changed no one’s mind about military force, but most of the leaders at least agreed with his assessment that Mr. Assad’s government was responsible for the attack, something Mr. Putin has dismissed as “utter nonsense.”

“I’ve been encouraged by my discussions with my fellow leaders this week,” Mr. Obama said Friday. “There is a growing recognition that the world cannot stand idly by.”

But he acknowledged the deep reservations over the use of force and said he reminded the leaders at the dinner that he had opposed Mr. Bush’s invasion of Iraq in 2003. “I was elected to end wars, not start them,” Mr. Obama said he told them.