You're repeating the opposite of what Chivers wrote, Dave. The rusty remnants were made for the Iraq-Iran war (when my daughter was in Baghdad as secretary of Canada's ambassador to Iraq).

Rusted shells and mustard/sarin residue aren't the WMD's that the US went to war to remove. They were, from your quote above,"chemical weapons remaining from years earlier in Saddam Husseins rule."

ISIS wouldn't look at acknowledged junk, having access to all the arms and technology literally handed over to them by the US's expensively trained and equipped Iraqi army.