Syrian rebels have likely used sarin gas, according to on-the-record statements by a U.N. investigator this weekend. That news—hitting while the United States is still deciding how to respond to intelligence reports suggesting the Syrian government has used chemical weapons of its own—had U.N. investigator Carla del Ponte initially "stupefied."
Del Ponte told Swiss TV that investigators have "very strong suspicions, concrete suspicions that sarin gas has been used" by rebel forces, based on testimonies from victims and doctors in neighboring countries. As she cautioned, that's not "irrefutable proof" that the opposition used the chemical weapon. But her language sounded much more confident than Defense Secretary Chuck Hagel's statement that United States believes "with some degree of varying confidence" that President Assad's forces have used "small scale" chemical weapons in the conflict.
In any case, the U.N's findings could shake up the international conversation on what to do, or not do, about Syria. While the news might be surprising to many in the West, del Ponte did offer up one explanation to the AFP, citing reports that "the opponents have been infiltrated by foreign fighters." She also explained that the U.N. had no evidence as of now of the Syrian regime using chemical weapons, but they haven't ruled it out. For their part, representatives of opposition forces in the country have flatly denied any use of chemical weapons.
The rebels and the Syrian government have previously traded accusations over the alleged use of chemical weapons in the ongoing Syrian conflict. As Reuters notes, there are three specific attacks around which these accusations focus: a December attack near Homs, and two attacks in March, near Aleppo and Damascus. And while the opposing sides in the conflict routinely push wildly different narratives of horrific incidents in the country, the sarin gas accusations carried a unique weight: President Obama had previously suggested that chemical weapons use by the Assad regime was the U.S.'s "red line," a statement that was widely viewed as a suggestion that western military intervention would follow the crossing of that line. Of course, as Slate's Fred Kaplan explains, that's not exactly how things have played out.