Analysis of soil and blood samples has given U.S. intelligence agencies moderate to strong levels of confidence that the Bashar Assad regime has used chemical weapons in the Syrian civil war, the New York Times quoted a key lawmaker as saying on Thursday.
The White House, according to Senate intelligence committee Chairwoman Dianne Feinstein (D-Calif), did not indicate a corresponding level of confidence in a letter this week to several top lawmakers, which stated that "the U.S. intelligence community assesses with some degree of varying confidence that the Syrian regime has used chemical weapons on a small scale in Syria."
U.S. intelligence officials derived their conclusions from the results of soil analysis and testing of blood taken from survivors of two purported chemical attacks in March -- one close to Damascus and the other not far from Aleppo.
The Obama administration said the "chain of custody" of the warfare materials that were used is not known, which means their usage might not necessarily have been intentional.
The White House has said repeatedly that use or proliferation of chemical weapons in the Syrian civil war -- which has already killed more than 70,000 people -- would cross a "red line" that would demand an unspecified U.S. intervention. On Friday, though, spokesman Jay Carney stressed the need to confirm allegations.
"The facts need to be what drives this investigation, not a deadline," Reuters quoted Carney as saying. "We are continuing to work to build on the assessments made by the intelligence community, that the degrees of confidence here are varying, that this is not an airtight case."
He said possible responses "include but are not exclusive to [the military] option."
The United States is calling for a U.N. investigative team to enter Syria to gather information and more evidence from the scenes of the alleged chemical attacks. The Assad government requested the inquiry but has refused entry to the team until the scope of the probe is agreed upon.
Still, Washington demonstrated on Thursday that it feels enough proof has already been gathered to come to an initial conclusion. The administration is also concerned about a possible separate chemical assault in Homs, an anonymous official told the Times.
Two intelligence sources said there were some elements of the U.S. finding on chemical use that were not as strong as others. No other specifics were disclosed to the newspaper.
Testing of blood samples withdrawn from multiple people affirmed the presence of the nerve agent sarin, a U.S. intelligence source told Wired on Thursday.
"This is more than one organization representing that they have more than one sample from more than one attack. But we can't confirm anything because no [one] is really sure what's going on in country," the source said.
Sarin is a highly volatile and deadly warfare material that is not easily made or deployed. It attacks breathing and muscle control functions and can cause death in minutes.
"It would be very, very difficult for the opposition to fake this. Not only would they need the wherewithal to steal it or brew it up themselves," the source said. "Then they'd need volunteers who would notionally agree to a possibly lethal exposure."
A high-ranking unidentified Pentagon official told journalists that use of the wording "varying degrees of confidence" typically means there is disagreement between U.S. intelligence branches about certain findings, Reuters reported.
Syrian Deputy Foreign Minister Faisal Mekdad told Reuters there was no merit to the accusations by France, Israel, the United Kingdom, and now the United States of chemical weapon usage. He also insisted that Damascus is not obstructing the U.N. inquiry.
Assad forces "did not and will not use chemical weapons even if it had them," the Associated Press quoted an unidentified Syrian government insider as saying on Friday. The source accused rebels of carrying out the alleged March 19 gas attack near Aleppo, and insisted the regime did not require such agents "because it is capable of reaching any area in Syria it wants."
A White House official said the Obama administration will talk with partner nations in determining how to respond to the situation. "All options are on the table in terms of our response."
An unidentified high-ranking Obama official said "we are continuing to do further work to establish a definitive judgment as to whether or not the red line has been crossed," Foreign Policy reported. "If we reach a definitive determination that this red line has been crossed ... what we will be doing is consulting with our friends and allies and the international community more broadly, as well as the Syrian opposition, to determine what the best course of action is."
The United States is collaborating with Syrian rebels to collect more proof of chemical attacks from inside the Arab country that would be used to build a more comprehensive finding, the Wall Street Journal reported, citing a White House official.
British Prime Minister David Cameron on Friday said there was "limited" though "growing evidence" that chemical arms had been utilized, likely by Assad loyalists, the Times reported.
The United States and the United Kingdom are wary of getting too far ahead of the evidence in Syria as they wish to avoid a repeat of the WMD intelligence fiasco in Iraq.
The British government has no desire to get involved in another military conflict, Cameron said.
Israeli Deputy Foreign Minister Zev Elkin, who is close with Prime Minister Benjamin Netanyahu, on Friday said the Obama administration should seriously think about carrying out a U.S. military intervention in Syria, Reuters reported.