Chemical weapons in Syria and the standards of evidence
British prime minister David Cameron has weighed in today on the question of whether the Syrian regime is using chemical weapons telling the BBC there is "limited but growing" evidence that troops have used poison gas. It follows the U.S. administration's assertion yesterday that American intelligence had "varying degrees of confidence" that the regime has used the nerve agent sarin on a "small scale" but corroborated, conclusive evidence is needed.
So far, soil samples or physiological evidence were examined by the British, American and French outside Syria. This presents a set of problems if America and its allies are considering intervening in Syria on the basis that President Bashar Assad has, in Barack Obama's phrase, crossed a "red line."
The incidents are not linked to specific, credible events, observes Jeffrey Lewis, a leading expert on nuclear non-proliferation.
"First, the allegation of chemical weapons use needs to be specific to a time and place. We need a date, time, location, and (ideally) the identity of the Syrian unit in question. What we want to be sure of is that an actual military attack occurred that resulted in victims. Second, once we have an attack, we need victims of that attack. These victims, who can credibly be placed on the receiving end of the attack, will provide blood or urine samples that show sarin use."
He continued: "We have to be certain that any sarin exposure resulted from an attack. Having set a red line for U.S. involvement to deter Assad, we’ve also created an incentive for certain groups to tell stories that might result in more U.S. assistance. As I’ve noted before, these groups don’t appear particularly scrupulous when it comes to the truth. So I’d be very, very careful about leaping to conclusions."
The battlefield is unpredictable. Lewis recalled that in 1991 American soldiers detonated a pit of munitions at Khamisiyah in Iraq only to discover that the munitions contained sarin, exposing thousands of U.S. service personnel to low levels of sarin.
"There are many ways that Free Syrian Army fighters might find themselves exposed to sarin. I still think caution is important," he wrote.
The UN is waiting for Syria to allow a team of investigators inside the country to examine claims that chemical weapons are being used. This may be the best chance of establishing the full truth.
But how likely is it that the Syrian regime, if indeed it has gassed people, would allow the UN access?
Syria is not a signatory to the Chemical Weapons Convention but the use of chemical weapons is a war crime under international law and attackers would be hauled in front of an international court.
Hamida Ghafour is a foreign affairs reporter at The Star. She has lived and worked in the Middle East and Asia for more than 10 years and is the author of a book on Afghanistan. Follow her on Twitter @HamidaGhafour