Roughly four months before the split between the Nusra Front and ISIS, in December 2012, dozens of Syrian jihadi fighters climbed a hill toward Regiment 111 a large army base near the town of Darat Izza, in northern Syria. That town had been taken roughly five months earlier by a coalition of rebel groups. But while they had besieged Regiment 111 since the summer of 2012, they still had not succeeded in capturing the base from the troops loyal to President Assad.
They found large stocks of weapons, ammunition and, to their surprise, chemical agents. They were, according to Abu Ahmad, mainly barrels filled with chlorine, sarin, and mustard gas.
What followed was the distribution of the war spoils. Everybody took some ammunition and weapons. But only the Nusra Front seized the chemical weapons. Abu Ahmad watched as the al Qaeda affiliate called in 10 large cargo trucks, loaded 15 containers with chlorine and sarin gas, and drove them away to an unknown destination. He did not see what happened to the mustard gas.
Three months later, both the Syrian government and rebel groups reported an attack in Khan al-Assal, near Aleppo. The international media said that 26 people had been killed, among them 16 regime soldiers and 10 civilians. Both the Syrian regime and opposition claimed that chemical weapons had been used and both accused the other of having carried out one of the first chemical weapons attacks in the Syrian war.
But in mid-August 2013, Abu Ahmed received news that made him think that ISIS had emerged from the split with the Nusra Front in possession of the chemical weapons seized at Regiment 111 and that it was now using them against its enemies.
Al-Hamra is located roughly 20 miles northeast of the city of Hama. It is still controlled by forces loyal to the Syrian government.
Abu al-Atheer spoke of another ISIS chemical attack. We also used one car bomb filled with chemicals against regime forces near to Menagh Airbase, he said. Menagh Airbase is located roughly 20 miles north of Aleppo. After a year-long siege, on Aug. 5, 2013, Menagh Airbase was eventually overrun by jihadis led by ISIS.
Whether they are or not, the Islamic State appears to still have these weapons in their arsenal. More than two years later, on Oct. 6, 2015, the New York Times published an article describing how the Islamic State used chemical weapons against moderate rebel fighters in the northern town of Marea. According to the Times, the group fired projectiles that delivered sulfur mustard. This substance is more commonly known as mustard gas.
The Dutch-Turkish jihadi Salih Yilmaz, a former soldier in the Dutch Army who has joined IS, admitted on Aug. 31, 2015, on his now defunct blog that Islamic State indeed used chemical weapons there. Yilmaz was asked by a reader of his blog why did they accuse [the Islamic State] of recently using chemical weapons in Aleppo province?
Yilmaz responded by writing: Where do you think IS got their chemical weapons from? From our enemies and thus we use their own weapons against them.
Full article: http://foreignpolicy.com/2016/08/17/how-the-islamic-state-seized-a-chemical-weapons-stockpile/