This is the third claim of people being killed by poison gas in Syria in four months. The first two alleged that Assad’s forces were responsible, which is at least plausible logistically. It’s no secret that he has chemical WMD on the shelf and there’s no reason to think he has any moral objection to using it. And yet, there’s no hard reason to think that he has. Both of the earlier claims were dubious, with U.S. officials stepping forward in the second case to help debunk it. The White House has said before that chemical weapons are America’s “red line” in Syria, so if Assad finally takes the plunge, he’ll have to have reached a moment of such desperation that he no longer fears U.S. intervention as a result.

Any reason to think the rebels have chemical weapons of their own and might be willing to use them? Sort of. Back in December, a video circulated online purporting to show rebels gassing rabbits as a warning to Assad that they can play hardball too if need be. John Kerry warned literally yesterday about Assad’s weapons falling into terrorists’ hands, a possibility made more probable by reports of high-ranking Syrian military officials defecting to the rebels’ side. There have been reports now for months too that Assad’s troops have been “activating” part of his chemical stockpile by combining the precursors for gases like sarin. If the rebels managed to overrun an Assad arms depot and either got control of a fully assembled shell or got control of the precursors and had the expertise in their camp to put it together, then yeah, it’s kinda sorta possible that today’s story is true.

But wouldn’t they lose more from it than they gain?

Neither of the accusations could immediately be verified, and a chemical weapons expert in the U.K. told CBSNews.com there was very little evidence to suggest any actual chemical weapons had been deployed. A U.S. official, speaking anonymously to the Associated Press, also said there was no evidence of a chemical attack. Also expressing doubts was the Organization for the Prohibition of Chemical Weapons, which reported no independent information of chemical weapons use.

At the White House, spokesman Jay Carney told reporters the administration had no evidence to suggest the rebels had used chemical weapons, but added: “We are looking carefully at the information as it comes in… This is an issue that has been made very clear by the president to be of great concern to us.”…

Russia, one of the Syrian regime’s few remaining allies, joined the Assad regime in accusing the rebels of carrying out a chemical attack, calling it an “extremely dangerous” development in the crisis. The Foreign Ministry in Moscow said rebels had detonated a munition containing an unidentified chemical agent early Tuesday in Aleppo province, without giving further details. The claim was nearly identical to the reports by Syria’s state media…

“I saw mostly women and children,” the Reuters photographer, who was not identified, told his editors. He said after visiting the University of Aleppo hospital and the al-Rajaa hospital — both in state-controlled parts of Aleppo — that victims “said that people were suffocating in the streets and the air smelt strongly of chlorine.”

A chemical weapons expert tells CBS that even conventional weapons can produce a chlorine-type smell, and that if deadly gas had been involved, the doctors at the hospital who treated the victims would be affected too since they weren’t wearing protective clothing. Besides, what sense would it make for the rebels to risk complicating the west’s anti-Assad position by using WMD on a random bunch of civilians? The U.S. has provided aid, both overt and covert, to the opposition but that’ll become untenable if they start breaking out the sarin. To preserve any chance of a more robust American intervention on their behalf later, the rebels have to be careful not to do anything too politically toxic. As such, if chemical weapons do end up being used, it makes more sense strategically and logistically that Assad’s forces will end up using them and trying to pin it on the rebels to spoil their international support.

Speaking of politically toxic Syrian rebels, take a gander at this LA Times piece from over the weekend. The CIA’s not waiting for Assad to fall to figure out which jihadis in the opposition have a rendezvous in their future with American drones.