on 17 September 1980, Iraq suddenly abrogated the Algiers Protocol following the Iranian revolution. Saddam Hussein claimed that the Islamic Republic of Iran refused to abide by the stipulations of the Algiers Protocol and, therefore, Iraq considered the Protocol null and void. Five days later, the Iraqi army crossed the border.
The next day, Iraq launched a ground invasion along a front measuring 644 km (400 mi) in three simultaneous attacks. The invasion's purpose, according to Saddam, was to blunt the edge of Khomeini's movement and to thwart his attempts to export his Islamic revolution to Iraq and the Persian Gulf states.
Though the Iraqi air invasion surprised the Iranians, the Iranian air force retaliated the day after with a large-scale attack against Iraqi air bases and infrastructure in Operation Kaman 99. Groups of F-4 Phantom and F-5 Tiger fighter jets attacked targets throughout Iraq, such as oil facilities, dams, petrochemical plants, and oil refineries, and included Mosul Airbase, Baghdad, and the Kirkuk oil refinery.
On 24 September, the Iranian Navy attacked Basra, Iraq, destroying two oil terminals near the Iraqi port Faw, which reduced Iraq's ability to export oil. The Iranian ground forces (primarily consisting of the Revolutionary Guard) retreated to the cities, where they set up defences against the invaders.