White House Confirms Syria Chem Weapons Use Likely

The White House said Thursday that Syria had likely used chemical weapons against rebel forces on a "small scale," but emphasized U.S. spy agencies were still not 100 percent sure of the assessment.

A senior U.S. administration official commented on the news, saying that "all options are on the table" if it is confirmed that Syria has used chemical weapons against opposition forces.

The official, speaking on condition of anonymity, said Washington wants to be absolutely sure that Syria has used chemical weapons before concluding that Damascus has crossed a "red line," triggering possible military action.

U.S. intelligence services had been investigating reports that Syrian President Bashar Assad's forces had used chemical arms -- a move Washington has said would cross a "red line," triggering possible military action.

"Our intelligence community does assess with varying degrees of confidence that the Syrian regime has used chemical weapons on a small scale in Syria," U.S. National Security Council spokeswoman Caitlin Hayden said.

The assessment, which she said was based in part on "physiological samples," points to the possible use of sarin, a man-made nerve agent used in two attacks in Japan in the 1990s. It can cause convulsions, respiratory failure and death.

Hayden however warned the chain of custody of the weapons was "not clear, so we cannot confirm how the exposure occurred and under what conditions."

"Given the stakes involved, and what we have learned from our own recent experience, intelligence assessments alone are not sufficient," she said.

U.S. Defense Secretary Chuck Hagel, speaking in Abu Dhabi, said the decision to release the intelligence report had been "made within the past 24 hours" and warned that use of such weapons "violates every convention of warfare."

In London, Britain's Foreign Office too said it had "limited but persuasive" evidence of the use of chemical agents in Syria's grinding civil war, which the U.N. says has left more than 70,000 people dead since it began in March 2011.

Mounting evidence of chemical weapons attacks on fighters battling Assad's regime could increase the pressure on U.S. President Barack Obama -- who has sought to avoid any U.S. military role in the conflict -- to intervene.

His administration laid out the intelligence assessment in a letter to U.S. lawmakers from Miguel Rodriguez, director of the White House office of legislative affairs.

"We do believe that any use of chemical weapons in Syria would very likely have originated with the Assad regime," the letter said.

So far, U.S. intelligence indicates that "the Assad regime maintains custody of these weapons, and has demonstrated a willingness to escalate its horrific use of violence against the Syrian people," the letter said.

Earlier this week, an Israeli general in military intelligence alleged that Syria had used chemical agents more than once during the protracted civil war, after Britain and France had voiced similar concerns to the United Nations.

Last month, during a historic visit to Israel, Obama said the use of such weapons would be a "grave and tragic" mistake on Assad's behalf and that it would be a "game changer."

Asked if the intelligence assessment meant that Syria had passed the declared "red line," Hagel said that was a policy question and that his task was to provide the U.S. president with "options."

Chemical weapons are "uncontrollable deadly weapons" that most leaders view as being in a "different category," Hagel said at the end of a Middle East tour with meetings in Israel, Jordan, Saudi Arabia, Egypt and the United Arab Emirates.

Senior U.S. Senator John McCain, who was one of the lawmakers who received a letter from the administration about Syria, said the key now was to ensure chemical weapons did not fall into the wrong hands.

"Some of them are in heavily contested areas and could easily fall into the hands of jihadist extremists," he told CNN.

Meanwhile, members of Congress urged Obama later on Thursday to take action to "secure" Syria's chemical weapons after he warned that Assad used them against his own people.

Republican Senator John McCain led the revulsion and anger in Congress, saying it was now up to Obama to coordinate a response that prevents such weapons, including the agent sarin, from falling into the hands of terrorists or extremist groups.

Obama "said that if Bashar Assad used chemical weapons, it would be a game-changer, that it would cross a red line. I think it's pretty obvious that a red line has been crossed," McCain told reporters.

"We have to have operational capability to secure these chemical weapon stocks," he added. "We do not want them to fall into the wrong hands, and the wrong hands are a number of participants in the struggle that's taking place in Syria."

For months the veteran Republican has urged Obama to take a more pro-active role in the Syrian conflict and pressed him to help arm Syrian rebels and ensure safe havens in the country.

On Thursday he called for increased White House pressure on Russia and Iran to stop supplying weapons to Assad, and greater commitment to aid Syria's rebel groups fighting Damascus.

"The situation on the ground today is stalemate, with the Iranians and the Russians all in, and the United States of America gives them (Syrian rebels) flak jackets. That is not comforting when Scud missiles are hitting you."

Democrat Dianne Feinstein, chair of the Senate Intelligence Committee, concurred that "red lines have been crossed" in Syria.

"Action must be taken to prevent larger scale use. Syria has the ability to kill tens of thousands with its chemical weapons," she said in a statement.

"The world must come together to prevent this by unified action which results in the secure containment of Syria's significant stockpile of chemical weapons."

Republican Howard "Buck" McKeon, chairman of the House Armed Services Committee, said Assad's use of chemical weapons on the Syrian people, if true, is "an astounding violation of human rights," and triggers a "national security imperative."

Obama now has "a deep moral imperative" to act, McKeon said.

Republican Senator Saxby Chambliss said the chemical weapons revelation "changes the game."

Asked what the next U.S. step should be, Chambliss told AFP: "that's for our military folks to tell us."

However, officials traveling with Hagel in the Middle East suggested military action against Syria was not a certainty -- at least for the moment.

"It's our job... to present options to the president upon request," the senior defense official, who spoke on condition of anonymity, told reporters in Abu Dhabi.

But the official added: "Intelligence assessments don't automatically trigger policy decisions. It's important to note in this case."

Alluding to the disastrous intelligence failure in the run-up to the 2003 U.S. invasion of Iraq, the official indicated the White House would be careful not to allow intelligence reports to drive a decision to use military force.

Former officials and analysts say the United States could try to secure Syria's chemical arsenal by sending in special forces teams and launching bombing raids.

But any military action would be high-risk with a chance that weapons could fall into the hands of extremists.

Deploying troops would require warplanes to knock out Syria's air defenses first, allowing special forces to be flown in, experts say.

The Pentagon has already sent more than 200 troops to Jordan, including a U.S. Army headquarters element, to prepare for a possible joint operation with allies to secure chemical weapons.