WASHINGTON -- Even as lawmakers pressed President Barack Obama on Thursday to take more aggressive action in Syria, questions surfaced among experts and from within the U.S. government about the strength of the evidence showing that chemical weapons have been used in that nations 2-year-old civil war.
White House officials set off a fervor on Capitol Hill when they acknowledged for the first time that the United States had received some evidence that Syrian President Bashar Assad had used chemical weapons, the lethal nerve agent sarin in particular.
Secretary of Defense Chuck Hagel told reporters Thursday in Abu Dhabi that the conclusion had been made in the previous 24 hours.
We cannot confirm the origin of these weapons, but we do believe that any use of chemical weapons in Syria would very likely have originated with the Assad regime, he said. As Ive said, this is serious business. We need all the facts.
But experts say the reports should be met with some skepticism because of the small amount of sarin that was found, the lack of widespread deaths and injuries, and inconclusive U.S. intelligence assessments.
The intelligence findings cited in a letter from the White House to Capitol Hill on Thursday were of low or moderate confidence, said a U.S. intelligence official who requested anonymity in order to discuss the classified reports.
Another person familiar with the issue, who asked not to be further identified because of its sensitivity, said that only a minuscule trace of a byproduct a toxic residue left behind after use of a nerve agent, and which he did not identify had been found in a soil sample.
They found trace amounts of a byproduct in soil, but there are also fertilizers that give out the same byproduct, the person said. Its far from conclusive.
Obama has long resisted significant involvement in Syria, despite repeated calls to help end the bloodshed in the war-torn country. But he has said repeatedly that the use of chemicals weapons would trigger what he called a red line and lead to greater intervention.
So far, the United States has provided hundreds of millions of dollars in aid to Syrians seeking to overthrow the Assad regime and has called on the United Nations to investigate the possible use of chemical weapons. That inquiry has been blocked by Assad.
After two years of brutal conflict, its past time for the president to have a robust conversation with the Congress and the American people about how best to bring Assads tyranny to an end, said House Speaker John Boehner, R-Ohio.
Sen. John McCain, R-Ariz., called the disclosure a game changer.
Lawmakers of both parties are calling on Obama to provide a safe area for the opposition to operate, to establish a no-fly zone and to offer weapons to the resistance.
It is clear that we must act to assure the fall of Assad, the defeat of extremist groups, and the rise of democracy, said Sen. Robert Menendez, D-N.J., chairman of the Senate Foreign Relations Committee. We must do everything possible to prevent the regimes use of chemical weapons and to ensure those stockpiles are secure.
Administration officials said that all options are on the table, but they cautioned that it is too early to judge whether the U.S. should get further involved. Information about the quantity of sarin and the injuries or deaths caused by it were not released, and administration officials raised questions about the chain of custody of physiological evidence.
Two of the worlds leading experts on chemical weapons not privy to the details of the assessments urged caution.
Jean Pascal Zanders, a senior researcher at the European Union Institute for Security Studies, said that a video broadcast internationally showing the effects of the alleged attack doesnt necessarily comport with a sarin attack. He said it could represent a number of other problems, including drowning.
And there were other possible red flags in the video.
Why only one person? he said, referring to the video showing one patient it said was a victim. Why do I find the hospital setting, again, unlike what I would expect in a case of chemical exposure? Why is the guy foaming in the hospital, considering the rapid action of sarin. Zanders explained that without an antidote, death is possible within one minute after exposure to sarin.
Richard Guthrie, formerly project leader of the Chemical and Biological Warfare Project of the Stockholm International Peace Research Institute, said the number of those affected appears low. He said, for example, the Tokyo underground attacks in 1995 that involved a small amount of sarin resulted in 13 deaths and more than 1,000 wounded.
Any kind of a large-scale attack would have left a lot of dead, and a lot more showing symptoms, Guthrie said.
Even if there was certain sarin contamination, he said the apparent small effect would raise questions about whether it might have been the result of a mistake, a rebel attack somehow damaging a Syrian chemical weapon in transit, or as happened on several occasions in the Iran-Iraq war, a single poorly labeled artillery shell being used accidentally.
Even that would seem to fall short of a red line, Guthrie said.
After Hagels statement, the White House released a letter to McCain and Sen. Carl Levin, D-Mich., chairman of the Senate Armed Services Committee, who on Wednesday had asked Obama for information about Syria.
Our intelligence community does assess with varying degrees of confidence that the Syrian regime has used chemical weapons on a small scale in Syria, specifically the chemical agent sarin, wrote Miguel Rodriguez, the White Houses director of legislative affairs.
Earlier this week, U.S. officials, including Secretary of State John Kerry and White House spokesman Jay Carney, declined to say whether the United States agrees with three major allies Israel, Britain and France that Syria had used chemical weapons. They did an about-face Thursday.
Weve seen the White House do a 180, said Reva Bhalla, a Middle East analyst at Stratfor, a private global intelligence firm.
Bhalla said the White House was under growing pressure to at least acknowledge its allies findings.
Theres no debate about whether Syria has a chemical weapons stockpile. International experts agree that the Assad regime is believed to have hundreds, if not thousands, of weapons filled with chemical agents.
David Lightman and Hannah Allam of the Washington Bureau contributed.