“March 16 is the 33rd anniversary of the chemical carnage in Halabja, Some care not to remember—those in the west who provided Saddam with the deadly chemicals. Over 5,000 innocent civilians were gassed to death. Still want to talk about "malign regional behavior"? Shameless.” Zarif said on Twitter.

The Halabja chemical attack, also known as the Halabja Massacre or Bloody Friday was a massacre of Kurdish people that took place on 16 March 1988, during the closing days of the Iran–Iraq War in the Kurdish city of Halabja in Iraqi Kurdistan.

The attack was part of the Al-Anfal Campaign in Kurdistan, as well as part of the Iraqi Army's attempt to repel the Iranian Operation Zafar 7. It took place 48 hours after the capture of the town by the Iranian Army. A United Nations (UN) medical investigation concluded that mustard gas was used in the attack, along with unidentified nerve agents.

The incident was the largest chemical weapons attack directed against a civilian-populated area in history, killing between 3,200 and 5,000 people and injuring 7,000 to 10,000 more, most of them civilians. Preliminary results from surveys of the affected region showed an increased rate of cancer and birth defects in the years afterward.

The Halabja attack has been officially defined by the Supreme Iraqi Criminal Tribunal as a genocidal massacre against the Kurdish people in Iraq under Saddam Hussein.