The U.N. commission member's statement has not been confirmed, including by the United Nations itself, which put out a statement clarifying that it has not found any conclusive proof of chemical weapons use. The allegation that rebels may have used chemical weapons appears to be based on interviews with witnesses and Syrian health workers, rather than on first-hand investigation.
If this assertion were proven true, it would raise a number of important questions about the Syrian conflict. If the chemical taboo is broken in Syria, does that make the regime more likely to use those weapons itself? Would rebel use of chemical weapons lead foreign powers to reduce their support for the Syrian opposition? At what point does the United States or Jordan activate its nearby troops, which are on standby to secure loose chemical weapons in a worst-case scenario?
Whether this latest report is true or not, though, the ongoing uncertainty about Syria's chemical weapons is revealing in itself. The shifting reports appear to suggest that the exposure may have been small, as a large-scale attack would have presumably drawn more attention and thus more witness accounts. It's also a reminder of how difficult it is to piece together events in a far-away war zone, particularly in Syria, where the front lines are fluid and many of the troops irregular. Keep that uncertainty in mind as the United States evaluates whether or how to respond to the possibility that President Obama's "red line" on chemical weapons may have been crossed.
Adding to the doubts, some analysts are now wondering if the attack might have actually involved chlorine, which is also a chemical weapon but can be bought over-the-counter. A March Reuters story described a possible chemical attack in the northern town of Khan al-Assal, near Aleppo, after which residents said they could smell chlorine. The Telegraph reported at the time that Syrian regime forces accused rebels of using a homemade chlorine solution in the attack.
As Foreign Policy's Blake Hounshell points out, Khan al-Assal was a regime-controlled area at the time, which suggests that if anyone were to attack it, it would probably be rebels. (Hat tip to Hounshell for resurfacing these March articles.)
Syria analyst Michael Weiss, also writing at the time, noticed that both Syrian state media and opposition groups independently reported the attack and blamed the other side. That's not something either side would seem likely to do if they had actually conducted the attack, particularly given the sensitivity around chemical weapons. Both appeared, in other words, equally surprised.
Perhaps adding some credibility to fears that Syrian rebels could potentially use chlorine, militants in neighboring Iraq used chlorine bombs several times in 2007. Some Syrian fighters with the Islamist rebel group Jabhat al-Nusra are believed to have ties to Iraqi extremists.
On the other hand, a senior State Department official said that the United States has no information to suggest that Syrian rebels have the intent or capability to use chemical weapons, according to CNN's Jill Dougherty.
Taken together, all of this information makes it difficult to say with much certainty whether or not chemicals are being deliberately deployed in Syria (in a country with such large stockpiles, accidental exposure is a possibility), much less by whom. It may indeed turn out that either government forces or the rebels are using chemical weapons. For now, we have a number of puzzle pieces, some of them suggesting very different conclusions, but no way to fit them together into a clear picture.