Iraqi invasion of Iran

The Iraqi invasion of Iran began on 22 September 1980, sparking the Iran–Iraq War, and lasted until 5 December 1980. Iraq attacked under the impression that Iran would not be able to respond effectively due to internal socio-political turmoil caused by the country's Islamic Revolution one year earlier. However, Iraqi troops became increasingly bogged down in the face of fierce Iranian resistance, which greatly stalled their advance into western Iran. In just over two months, the invasion was brought to a halt, but not before Iraq had managed to occupy more than 25,900 square kilometres (10,000 sq mi) of Iranian territory.

On 10 September 1980, Iraq, hoping to take advantage of a weakened Iran's consolidation of the Islamic Revolution, forcibly reclaimed territories in Zain al-Qaws and Saïf Saad; these had been promised to Iraq under the terms of the 1975 Algiers Agreement, but were never actually transferred. Both Iran and Iraq later declared the treaty as null and void, doing so on 14 September and 17 September, respectively. As a result, the only outstanding dispute along the Iran–Iraq border at the time of the Iraqi invasion on 22 September was the question of whether Iranian ships would fly Iraqi flags and pay navigation fees to Iraq while sailing through a stretch of the Shatt al-Arab spanning several kilometres. On 22 September, Iraqi aircraft pre-emptively bombarded ten Iranian airfields in an ultimately unsuccessful attempt to gain aerial superiority on the battlefield. On the next day, Iraqi troops crossed the international border in strength and advanced into Iran in three simultaneous thrusts along a front of approximately 644 kilometres (400 mi). Of Iraq's six divisions that were invading by land, four were sent to Iran's oil-rich Khuzestan in order to cut off Iranian access to the Shatt al-Arab and establish a territorial security zone.

Iraqi president Saddam Hussein presented the invasion as a strategically defensive measure to blunt the edge of Iranian politician Ruhollah Khomeini, who had risen to power as Iran's "Supreme Leader" and was attempting to export the Islamic Revolution to the Arab world. Saddam, as a secularist and an Arab nationalist, perceived Iran's Shia Islamism and Persian identity as an immediate and existential threat to his Ba'ath Party and thereby to Iraqi society as a whole. The Iraqi government sought to take control of the entire Shatt al-Arab in a rapid and decisive military campaign, believing that Iraq's victory in the broader conflict would humiliate Iran and lead to Khomeini's downfall, or, at the very least, thwart the new Iranian government's attempts to spread Khomeinism throughout the Muslim world. Saddam had also aspired to annex Khuzestan and saw the Islamic Revolution as an opportunity to do so, seeking to increase his country's prestige and power in the Arab world. To this end, his administration hoped that Iraq, as an Arab-majority country, could successfully exploit Arab separatism in Khuzestan to undermine Iran from within. In practice, these objectives failed to materialize and the majority of Iranian Arabs were indifferent to the pan-Arabism espoused by Iraq's Ba'athists.