Who's providing rebels with chemical weapons

"The terrorist group Isis is recruiting “highly trained professionals” to make chemical weapons – and has already used them in an attack." "It was reported in March that Isis had been attacking Iraqi soldiers with roadside bombs containing chlorine gas in fighting around Tikrit, after footage emerged showing plumes of orange smoke emerging for the bombs. It follows similar allegations that the extremists had released toxic gases in the eastern district of Kobani, during the siege of the town on the Syrian border, although it could not be confirmed."