On 28 June 1987, Iraq dropped mustard gas bombs on Sardasht, West Azerbaijan, Iran. In two separate bombing runs on four residential areas, the attack killed 130 people and injured 8,000. The gas attacks occurred during the Iran–Iraq War when Iraq frequently used chemical weapons against Iranian civilians and soldiers.
In 2006, a quarter of the town's 20,000 residents were still experiencing severe illnesses from the attacks. The film Walnut Tree (2020) was inspired by the event.