Saddam-Era Chemical Weapons in ISIS's hands - Wait, wha?!

So the popular talking point among opponents of the invasion of Iraq in the US is that "there were no WMDs". Someone might want to tell ISIS, which just recently too control of a Saddam-era chemical weapons complex in Iraq. Soooooo... kind of wondering how long this myth is going to continue to persist in the American public.

The jihadist group bringing terror to Iraq overran a Saddam Hussein chemical weapons complex on Thursday, gaining access to disused stores of hundreds of tonnes of potentially deadly poisons including mustard gas and sarin.
Isis invaded the al-Muthanna mega-facility 60 miles north of Baghdad in a rapid takeover that the US government said was a matter of concern.
The facility was notorious in the 1980s and 1990s as the locus of Saddam’s industrial scale efforts to develop a chemical weapons development programme.
Isis has shown ambitions to seize and use chemical weapons in Syria leading experts to warn last night that the group could turn to improvised weapons to carry out a deadly attack in Iraq.
Hamish de Bretton-Gordon, a former commander of Britain’s chemical weapons regiment, said that al-Muthanna has large stores of weaponized and bulk mustard gas and sarin, most of which has been put beyond ready use in concrete stores.