The U.S. on Thursday accused Syrian President Bashar Assad’s regime of having used chemical weapons, specifically the deadly nerve agent sarin, against rebels seeking to topple him.
But top officials, citing the flawed intelligence that led to the invasion of Iraq, said Washington needs to build what one called an “airtight” case before escalating America's military role in the Syrian civil war.
“We still have some uncertainties about what was used, what kind of chemical was used, where it was used, who used it,” Defense Secretary Chuck Hagel told reporters in Abu Dhabi, United Arab Emirates. Still, he said, “it violates every convention on warfare.”
President Barack Obama has repeatedly warned that he would consider Assad's use of chemical weapon a "red line" that could trigger the use of American military force in Syria, where the two-year conflict has left at least 70,000 dead.
"The president has made it clear that the use of chemical weapons or the transfer of such weapons to terrorist groups would be unacceptable," Hagel said. "The United States has an obligation to fully investigate—including with all key partners and allies, and through the United Nations—evidence of chemical weapons use in Syria."
The disclosure came after Britain, France and Israel separately said they had evidence that chemical weapons had been used in Syria. top U.S. officials including Secretary of State John Kerry and Hagel had rebuffed reporters' questions about those findings.
Kerry, Deputy Secretary of Defense Ashton Carter, Vice Chairman of the Joint Chiefs Admiral Sandy Winnefeld and Deputy Director of National Intelligence Robert Cardillo planned to brief lawmakers Friday morning on Syria and North Korea.
Obama's director of legislative affairs, Miguel Rodriguez, spelled out some of the details on Assad's alleged use of chemical weapons in a letter to Senate Armed Services Committee Chairman Carl Levin, D-Mich., and Republican Sen. John McCain of Arizona.
"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," Rodriguez wrote. "Given the stakes involved, and what we have learned from our recent experience, intelligence assessments alone are not sufficient—only credible and corroborated facts that provide us with some degree of certainty will guide our decision-making."
According to the Centers for Disease Control, sarin was used in terrorist attacks in Japan in 1995 and potentially during the Iran-Iraq war in the 1980s.
The intelligence assessment sparked fresh calls from both parties in Congress for the U.S. to take a greater role in helping rebel forces looking to oust Assad.
"President Obama correctly said that Syria's use of chemical weapons would be a red line for the United States. Now that we have confirmed their use, the question is what is our plan for transition to a post-Assad Syria?" Republican House Intelligence Committee Chairman Mike Rogers said in a statement. "I have laid out several steps, short of boots on the ground. The world is waiting for American leadership.”
Senate Intelligence Committee Chair Dianne Feinstein concurred, saying "action must be taken" to prevent Assad from escalating use of the deadly agent.
“I am very concerned that with this public acknowledgement, President Assad may calculate he has nothing more to lose and the likelihood he will further escalate this conflict therefore increases," Feinstein said in a statement. "It is also important that the world understands the use of weapons of mass destruction, such as sarin, will not be countenanced, and clearly Assad must go."
Not so fast, the administration responded. "We need all the facts. We need all the information," Hagel said.
In a conference call with reporters organized by the White House on Thursday, a senior Obama aide also pressed for more documentation.
"It’s precisely because we take this ‘red line’ so seriously that we believe there’s an obligation to fully investigate any and all evidence of chemical weapons use within Syria," he said.
The U.S. wants a full U.N. investigation but is also working with its allies and the Syrian opposition to gather more evidence.
"Given the stakes involved, given how serious the situation is, and what we’ve learned, frankly, from our own recent experience, intelligence assessments are not, alone, sufficient," the official said.
“I’d say that given our own history with intelligence assessments, including intelligence assessments related to weapons of mass destruction, it’s very important that we are able to establish this with certainty and that we are able to present information that is airthight in a public and credible fashion," he said, in an unmistakable reference to the flawed case for war in Iraq. "That is, I think, the threshold that is demanded."
The official said that if there was conclusive evidence the "red line" had indeed been crossed, the U.S. will consult with its allies and the Syrian opposition "to determine what the best course of action is."
The official said "all options are on the table in terms of our response"—an expression that typically refers to the use of force.