A border dispute between Iran and Iraq, which developed into a major war. In 1980 President Saddam Hussein of Iraq abrogated the 1975 agreement granting Iran some 518 sq km (200 sq miles) of border area to the north of the Shatt-al-Arab waterway in return for assurances by Iran to cease military assistance to the Kurdish minority in Iraq, which was fighting for independence. Calling for a revision of the agreement to the demarcation of the border along Shatt-al-Arab, a return to Arab ownership of the three islands in the Strait of Hormuz (seized by Iran in 1971), and for the granting of autonomy to minorities inside Iran, the Iraqi army engaged in a border skirmish in a disputed but relatively unimportant area, and followed this by an armoured assault into Iran's vital oil-producing region. The Iraqi offensive met strong Iranian resistance, and Iran recaptured territory from the Iraqis. In 1985 Iraqi planes destroyed a partially constructed nuclear power plant in Bushehr, followed by bombing of civilian targets which in turn led to Iranian shelling of Basra and Baghdad. The war entered a new phase in 1987 when Iran increased hostilities against commercial shipping in and around the Gulf, resulting in naval escorts being sent to the area by the USA and other nations. Senior officers of the Iranian army began to lose confidence as their troops suffered from shortages of arms and equipment, while Iraq continued to be supplied by the West. Early in 1988 the UN Security Council called for a ceasefire. Iraq agreed, but not Iran. Skilful negotiations by the UN Secretary-General, Pérez de Cuéllar, however, achieved an armistice in July and a peace settlement in August. Nothing had been gained, but an estimated 1.5 million lives were lost.