Obama Set for Limited Strike on Syria as British Vote No

President Obama is prepared to move ahead with a limited military strike on Syria, administration officials said Thursday, despite a stinging rejection of such action by America’s stalwart ally Britain and mounting questions from Congress.

The negative vote in Britain’s Parliament was a heavy blow to Prime Minister David Cameron, who had pledged his support to Mr. Obama and called on lawmakers to endorse Britain’s involvement in a brief operation to punish the government of President Bashar al-Assad for apparently launching a deadly chemical weapons attack last week that killed hundreds. 

The vote was also a setback for Mr. Obama, who, having given up hope of getting United Nations Security Council authorization for the strike, is struggling to assemble a coalition of allies against Syria. 

But administration officials made clear that the eroding support would not deter Mr. Obama in deciding to go ahead with a strike. Pentagon officials said that the Navy had now moved a fifth destroyer into the eastern Mediterranean Sea. Each ship carries dozens of Tomahawk cruise missiles that would probably be the centerpiece of any attack on Syria. 

Even before the parliamentary vote, White House officials said, Mr. Obama decided there was no way he could overcome objections by Russia, Syria’s longtime backer, to any resolution in the Security Council. 

Although administration officials cautioned that Mr. Obama had not made a final decision, all indications suggest that a strike could occur soon after United Nations investigators charged with scrutinizing the Aug. 21 attack leave the country. They are scheduled to depart Damascus on Saturday. 

The White House presented its case for military action to Congressional leaders on Thursday evening, trying to head off growing pressure from Democrats and Republicans to provide more information about the administration’s military planning and seek Congressional approval for any action. 

In a conference call with Republicans and Democrats, top officials from the State Department, the Pentagon and the nation’s intelligence agencies asserted that the evidence was clear that Mr. Assad’s forces had carried out the attack, according to officials who were briefed. 

While the intelligence does not tie Mr. Assad directly to the attack, these officials said, the administration said the United States had both the evidence and legal justification to carry out a strike aimed at deterring the Syrian leader from using such weapons again. 

A critical piece of the intelligence, officials said, is an intercepted telephone call between Syrian military officials, one of whom seems to suggest that the chemical weapons attack was more devastating than was intended. “It sounds like he thinks this was a small operation that got out of control,” one intelligence official said. 

But Republican lawmakers said White House officials dismissed suggestions that the scale of the attack was a miscalculation, indicating that the officials believe Syria intended to inflict the widespread damage. 

“I’m comfortable that the things the president told Assad not to do he did,” said Senator Lindsey Graham, Republican of South Carolina, who took part with seven other Republican senators in a separate briefing by the White House chief of staff, Denis R. McDonough. 

Among the officials on the conference call were Secretary of State John Kerry; Defense Secretary Chuck Hagel; the director of national intelligence, James R. Clapper Jr.; and the national security adviser, Susan E. Rice. It was unclassified, which means the administration gave lawmakers only limited details about the intelligence they assert bolsters the case for a military strike. 

Before the call, however, some prominent lawmakers expressed anger that the White House was planning a strike without significant consultations with Congress. “When we take what is a very difficult decision, you have to have buy-in by members and buy-in by the public,” Representative Mike Rogers, the Michigan Republican who is chairman of the House Intelligence Committee, said Thursday on MSNBC. “I think both of those are critically important and, right now, none of that has happened.”

Representative Eliot L. Engel of New York, the ranking Democrat on the House Committee on Foreign Affairs, said after the telephone briefing that administration officials “had no doubt that chemical weapons were used by Assad and his people.” 

Mr. Engel said that among the evidence described to members of Congress was an intercepted communication “from a high-level Syrian official” discussing the attack. “There is more than enough evidence if the president chooses to act,” Mr. Engel said. 

After the 90-minute conference call, some senior lawmakers were not persuaded that the Obama administration had made its case for military action in Syria. Representative Howard (Buck) McKeon, the California Republican who is chairman of the House Armed Services Committee, said Mr. Obama needed to make a forceful case to persuade both Congress and a “war weary” country.

“If he doesn’t, I think he could have a real problem with the Congress and the American public,” he said. “He’s got a big sell.” 

Several officials said that the intelligence dossier about the attack also includes evidence of Syrian military units moving chemical munitions into place before the attack was carried out.

Mr. Obama, officials said, is basing his case for action both on safeguarding international standards against the use of chemical weapons and on the threat to America’s national interest. 

That threat, they said, is both to allies in the region, like Turkey, Jordan and Israel, and to the United States itself, if Syria’s weapons were to fall into the wrong hands or if other leaders were to take American inaction as an invitation to use unconventional weapons. 

Mr. Obama’s rationale for a strike creates a parallel dilemma to the one that President George W. Bush confronted 10 years ago, when he decided to enter into a far broader war with nearly 150,000 American troops in Iraq without seeking an authorizing resolution in the United Nations. The Obama administration says that case differs sharply from its objectives in Syria.

In Iraq Mr. Bush was explicitly seeking regime change. In this case, White House officials argue, Mr. Obama is trying to enforce an international ban on chemical weapons and seeking to prevent their use in Syria, or against American allies. 

“We have been trying to get the U.N. Security Council to be more assertive on Syria even before this incident,” said Benjamin J. Rhodes, the deputy national security adviser for strategic communications. “The problem is that the Russians won’t vote for any accountability.” 

The decision to proceed without Britain is remarkable, however. Even in the Iraq war, Mr. Bush relied on what he called a “coalition of the willing,” led by Britain. Mr. Obama has made clear that this initiative would come from the United States, and that while he welcomed international participation, he was not depending on foreign forces for what would essentially be an operation conducted largely by the United States, from naval vessels off the Syrian coast. 

Mr. Rhodes and other aides rejected comparisons between this case and that of Mr. Bush in 2003, and noted that Mr. Obama was still actively seeking allied participation. “There is no direct parallel with 2003, given that the United States at that time had to prove the existence of weapons of mass destruction in a country where we were going to do a military intervention aimed at regime change,” Mr. Rhodes said. 

Mr. Obama has referred, somewhat vaguely, to reinforcing “international norms,” or standards, against the use of chemical weapons, which are categorized as “weapons of mass destruction” even though they are far less powerful than nuclear or biological weapons. 

In addition to the importance of upholding standards of international behavior, Mr. Obama this week has also highlighted America’s inherent right to self-defense. But some scholars warn that may be a difficult case for the United States to make. 

“Under this principle, Turkey, Jordan, Israel, Iraq or Lebanon could respond directly to Syrian belligerent acts, as could their allies, such as NATO and the U.S.,” said Phillip Carter, an analyst with the Center for a New American Security in Washington. He cautioned that despite the spillover from the violence, there still was no just cause for war with Syria by its neighbors. 

The United States has conducted unilateral bombing campaigns without seeking international endorsement before. But it made a direct case for self-defense.

In 1986, President Ronald Reagan ordered an airstrike on Tripoli after concluding that Libya was behind the bombing of a Berlin disco that killed two American military personnel. In 1998, after deadly bombings of American Embassies in Kenya and Tanzania, President Bill Clinton authorized cruise missile strikes on Afghanistan and Sudan.