U.N. Security Council members discussed Syria behind closed doors Thursday as British Prime Minister David Cameron argued the use of chemical weapons requires Western intervention in that nation's civil war.
Britain's Joint Intelligence Committee has concluded it was "highly likely" that Syrian government forces used poison gas outside Damascus last week in an attack that killed at least 350 people, according to a summary of the committee's findings released Thursday. Speaking in the House of Commons, Cameron said failure to respond would undo "decades of painstaking work" to prevent such weapons from being unleashed.
"The global consensus against the use of chemical weapons will be fatally unraveled," he said. "A 100-year taboo will have been breached."
But the debate appears to be putting the brakes on possible strikes against Syria, even as the United States moved an additional warship into the eastern Mediterranean Sea.
"It certainly seemed 48 hours ago that there was an all-party consensus that Parliament today would be endorsing the bombing of Syria this weekend, and I think people have pulled back from that," said Diane Abbott, a Commons member from the opposition Labour Party.
In Washington, White House spokesman Josh Earnest said President Barack Obama was still weighing a potential response, but said his administration was working on a "compressed timeline."
And in New York, the Security Council convened Thursday afternoon in a session called by Russia, Syria's leading ally, a Western diplomat told CNN.
U.N. weapons inspectors are now in Syria trying to confirm the use of chemical weapons. The inspectors are expected to leave the country by Saturday morning, Secretary-General Ban Ki-moon said Thursday.
Syrian President Bashar al-Assad's government denies using the weapons against opposition forces and says its troops were the victims, not perpetrators, of recent gas attacks; but both British and U.S. officials say the rebels have no capability to use poison gas on the scale of the August 21 attack near Damascus, which opposition sources said killed more than 1,300.
"There is no credible intelligence or other evidence to substantiate the claims or the possession of CW by the opposition," Britain's Joint Intelligence Committee concluded in a document released Thursday. "The JIC has therefore concluded that there are no plausible alternative scenarios to regime responsibility."
Cameron opened an emergency session of the Commons on Thursday by saying the debate was not about regime change or invasion. And he said his government would not act without first hearing from the U.N. inspectors, giving the world body a chance to weigh in and giving Parliament another chance to vote.
But the prime minister said failing to act would give Syrian President Bashar al-Assad the unmistakable signal that he could use poison gas "with impunity." The British dossier on Syria also concluded the Syrian government had used chemical weapons on 14 previous occasions, and Cameron said al-Assad stepped up their use last week as a sort of test for the world.
"He wants to know whether the world will respond to the use of these weapons," the prime minister said.
Many members of Parliament uneasy
But memories of more than a decade of bruising warfare in Iraq and Afghanistan hung over the debate, with many members sounding uneasy about committing British forces to another Middle Eastern conflict.
"We cannot ignore the calamitous lessons of the Iraq war. We need safeguards. We need a coherent strategy that takes into account the consequences," said MP Angus Robertson, the Scottish National Party's spokesman on defense issues. Without a clear understanding of the consequences and a legal basis for military action, Robertson said his party -- which holds six seats in the Commons -- would oppose any strikes.
The government said it could justify the use of force against Syria on humanitarian grounds, to stop the suffering, even if the United Nations declined to authorize a strike.
"The aim is to relieve humanitarian suffering by deterring or disrupting the further use of chemical weapons," the government said in a statement released Thursday.
Syria's government offered its own arguments against such an intervention. In an open letter to British lawmakers expected to vote Thursday on a motion blocking military action without a U.N. resolution, the speaker of Syria's parliament riffed on British literary hero William Shakespeare, saying: "If you bomb us, shall we not bleed?"
But in a veiled warning to the United Kingdom, the letter also invoked Iraq, a conflict justified on the grounds that Iraq had amassed stockpiles of chemical and biological weapons and was working toward a nuclear bomb -- claims that were discovered to have been false after the 2003 invasion.
"Those who want to send others to fight will talk in the Commons of the casualties in the Syrian conflict. But before you rush over the cliffs of war, would it not be wise to pause? Remember the thousands of British soldiers killed and maimed in Afghanistan and Iraq, not to mention the hundreds of thousands of Iraqi dead, both in the war and in the continuing chaos."
British Commons Speaker John Bercow published the letter, which was dated Thursday. And al-Assad has vowed to defend his country against any outside attack.
"The threats of launching an aggression against Syria will increase its commitments to its rooted principles and its independent decision that originated from the will of its people, and Syria will defend itself against any aggression," the Syrian president said Thursday in a speech to Yemeni politicians.
Obama faces calls for American vote on force
Across the Atlantic, Obama said in a televised interview Wednesday that he has no doubt Syria used chemical weapons on its own people. He said government claims that the opposition used them were impossible.
"We do not believe that, given the delivery systems, using rockets, that the opposition could have carried out these attacks. We have concluded that the Syrian government in fact carried these out. And if that's so, then there need to be international consequences," he said on "PBS NewsHour" Wednesday.
Obama said that he has not made a decision about whether to conduct a military strike in Syria. A senior administration official said the United States would continue to consult with British officials, but declined to say if the slowdown in London would affect U.S. decision-making on Syria.
Obama and his top advisers are holding extensive talks with American allies as they ponder their options. But the president is facing doubts at home as well: More than 160 members of Congress, including 63 Democrats, have now signed letters calling for either a vote or at least a "full debate" before any U.S. action.
The author of one of those letters, Rep. Barbara Lee, said Obama should seek "an affirmative decision of Congress" before committing American forces.
"While we understand that as commander-in-chief you have a constitutional obligation to protect our national interests from direct attack, Congress has the constitutional obligation and power to approve military force, even if the United States or its direct interests (such as its embassies) have not been attacked or threatened with an attack," wrote Lee, D-California.
More than 90 members of Congress, most of them Republican, signed another letter by GOP Rep. Scott Rigell of Virginia. That letter urged Obama "to consult and receive authorization" before authorizing any such military action.
Congress is currently in recess until September 9. But Sen. Tim Kaine said on CNN's "New Day" that "I definitely believe there needs to be a vote."
"I think there's ample work the president can do in consultation with the congressional leadership about this until we're back," said Kaine, a Virginia Democrat. "I think we are going to be back soon, and it would be completely consistent with the president's prudence up to this point for him to continue to have that dialogue."
Obama spokesman Earnest said Obama believes in "robust" consultations with Congress, and national security officials will provide an unclassified briefing for members of Congress on Thursday evening. Members will be invited to join a conference call with top administration officials, including National Security Adviser Susan Rice, Secretary of State John Kerry and Defense Secretary Chuck Hagel, he said.
"This call is something that we have been working to schedule for a number of days now, but it is just part of the ongoing, robust consultation that this administration believes is important for us to have with Congress," Earnest said. As for a vote on military action, that's "presupposing a decision that has not been made," he told reporters.