Secretary of State John F. Kerry said Sunday that fresh laboratory tests indicate sarin nerve gas was used in an Aug. 21 attack in Syria that killed more than 1,400 people, the first time that U.S. officials have pinpointed what kind of chemical weapon may have been involved.
Appearing on five television network talk shows, Kerry said blood and hair samples from emergency workers in east Damascus had tested positive for traces of sarin, a highly toxic nerve agent. He said that U.S. officials learned of the lab results in the past 24 hours, citing the evidence as yet another reason for Congress to pass President Obama's request to authorize the use of military force against the government of Syrian President Bashar al-Assad.
"This case is getting stronger," Kerry said on CBS's "Face the Nation." "The credibility of the United States is on the line here and I believe that Congress will do the right thing."
In an unclassified intelligence dossier made public Friday, U.S. officials had said they believed that the Syrian government had used "a nerve agent" in the Aug. 21 attack in the Damascus suburbs. But the intelligence report did not specify what kind of nerve gas was used and appeared to lack forensic evidence that would support a definitive conclusion.
Kerry told CNN's "State of the Union" that the blood and hair samples had "come to us through an appropriate chain of custody from east Damascus." He did not give further details or elaborate on the source of the material, other than to say that the evidence had not come from a team of United Nations inspectors that left Syria on Saturday.
The main Syrian Opposition Coalition said in a press briefing in Istanbul on Thursday that it had collected its own samples and made them available to the U.N. and "different world governments."
The coalition said that the samples were collected by medics in the Ghouta area of the Damascus suburbs "according to international standards" and were smuggled outside to neighboring countries.
The U.N. team of chemical weapons experts spent four days near the site of the alleged attack and brought an extensive collection of forensic samples and other evidence to The Hague for testing in European laboratories.
The results of those tests, depending on how quickly they are conducted, could now play an influential role as Congress debates whether to endorse military action against Syria. If the U.N. tests confirm that sarin gas was used, it would lend independent credibility to the Obama administration's assertions. If the U.N. tests are inconclusive or report conflicting results, however, they could badly undercut the White House.
U.N. officials had previously said it could take as long as two weeks for the chemical-weapons experts to complete their report. On Saturday, a spokesman for U.N. Secretary-General Ban Ki-moon said: "Whatever can be done to speed up the process is being done, but we are not giving a timeline."
Syria is believed to have multiple nerve agents and poison gases in its chemical weapons stockpile, including sarin. Assad's government has denied carrying out any attacks and has blamed rebel forces, without citing any evidence.
Officials from the Pentagon, State Department and White House were scheduled to give classified briefings to lawmakers Sunday afternoon, presumably with more details about the alleged use of sarin.
Congress is scheduled to return from recess Sept. 9, but Senate leaders said they would go ahead and hold hearings on Syria this week.
The new disclosure from Kerry came a day after Obama stunned lawmakers by putting on hold an imminent plan to launch military strikes against Syria. In a surprise announcement Saturday, Obama argued that the United States had a moral responsibility to respond forcefully to any use of chemical weapons, but would wait until Congress had a chance to weigh in.
Obama's decision postponed a military action that had appeared imminent, a prospect that had the Middle East on edge and stoked intense debate in the United States, where many dread getting dragged into a new war.