The most compelling argument made by those urging intervention in Syria is that the now infamous "redline" declared by President Obama — usage of chemical weapons – had been crossed. Israel, Great Britain and France had declared recently that evidence had pointed to chemical weapons being used.
Today in a report by the Guardian, it seems that western intelligence agencies are concerned they "can no longer prove for certain whether the Syrian government was responsible for alleged chemical weapon attacks, because initial samples and evidence trails have degraded over time."
It now seems that the United States and its allies may have to wait for further evidence of chemical weapons use before setting on a course of military action against Syria.
British Defense Secretary Philip Hammond noted the problem with relying on soil and blood samples before his talks with U.S. Secretary of Defense Chuck Hagel.
"The confidence that we are seeking degrades over time, and in order to have a properly measured chain of custody we would need to obtain samples after an[other] incident," noted Hammond.
Hammond also noted that if chemical weapons were used again that "we can detect further use."
"The regime will now be focused on the fact that the west will be looking for evidence."
There could be other issues with the evidence as well.
In a report from VOA, Gregory Koblenz, an expert on weapons of mass destruction and current Stanton Nuclear Security Fellow at the Council on Foreign Relations, explains that the West’s chemical warfare allegations against Syria are based on two basic forms of evidence, neither of which alone provides enough information about what really happened on the ground.
"One is video footage of alleged chemical attacks in Syrian hospitals,” he explained to VOA. "Some of the symptoms we see are consistent with exposure to a nerve agent like sarin, but the problem is that there are other chemicals that can cause similar reactions, and just the videos alone don’t provide enough information and context to really assess what happened to these people.”
Koblenz also has his doubts on human and soil samples.
"The provenance is murky, and that raises questions about whether these samples are really from the location they are said to be taken from, whether they were tampered with along the way, whether they stored properly to preserve the signatures within the samples to provide a useful analysis,” Koblenz explains.
Such analysis of the evidence posses challenges for the United States and concerned states on what steps to take next.
If Syria did use chemical weapons, and the West feels the case is not strong enough for some sort of military action, the Assad regime could just simply stop their use — essentially get a free pass on possible past deeds — in an attempt to avoid military action. Assad could also decide to use such weapons in very low concentrations, hoping he does not get caught because future evidence could also fail to meet the burden of proof.
Source(s) : Diplomat Magazine UAE