The attack is believed to have included the nerve agents Tabun, Sarin and VX, as well as mustard gas. Another possibility, according to the former senior CIA analyst Stephen C. Pelletiere, is that Iraq did not have the nerve agent to use in the attack but did have mustard gas which had been used in the Iran–Iraq War. It is occasionally suggested that cyanide was also included among these chemical weapons, though this assertion has been cast into doubt, as cyanide is a natural byproduct of impure Tabun. The attack on Halabja took place amidst the Anfal campaign, in which Saddam Hussein powerfully suppressed Kurdish revolts during the Iran–Iraq War.