Iraq invaded Iran on 22 September 1980, triggering a bitter eight-year war which destabilised the region and devastated both countries.
The then Iraqi leader Saddam Hussein claimed as a reason for the invasion a territorial dispute over the Shatt al-Arab, the waterway which forms the boundary between the two countries.
However, the conflict was rooted in regional rivalry.
Saddam Hussein felt directly threatened by the Islamic revolution which had brought Ayatollah Khomeini to power in Iran the year before.
