Excerpts from Books and Wikipedia
"The Kurdish peshmerga guerrillas, supported by Iran, liberated Halabja in the final phase of the Iran–Iraq War. On March 16, 1988, after two days of conventional artillery attacks, Iraqi planes dropped gas canisters on the town. The town and surrounding district were attacked with bombs, artillery fire, and chemical weapons, the last of which proved most devastating. At least 5,000 people died as an immediate result of the chemical attack and it is estimated that a further 7,000 people were injured or suffered long term illness. Most of the victims of the attack on the town of Halabja were Kurdish civilians.
The attack is believed to have included the nerve agents Tabun, Sarin, and VX, as well as mustard gas. Though, according to the former senior CIA analyst Stephen C. Pelletiere, Iraq did not have the nerve agent used in the attack, but did have mustard gas which was 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 infamous Anfal campaign, in which Saddam Hussein violently suppressed Kurdish revolts during the Iran–Iraq War. Before the war ended the Iraqis moved in on the ground and completely destroyed the town. In March 2010, the Iraqi High Criminal Court recognized the Halabja massacre as genocide; the decision was welcomed by the Kurdistan Regional Government." [Wikipedia]