On 7 June 1981, the Israeli air force destroyed Iraq's sole nuclear reactor under construction just outside Baghdad, in order to impede Iraq's nuclear weapons program. Following a series of PLO attacks in 1982, Israel invaded Lebanon that year to destroy the bases from which the PLO launched attacks and missiles into northern Israel. In the first six days of fighting, the Israelis destroyed the military forces of the PLO in Lebanon and decisively defeated the Syrians. An Israeli government inquiry—the Kahan Commission—would later hold Begin and several Israeli generals as indirectly responsible for the Sabra and Shatila massacre and hold Defense minister Ariel Sharon as bearing "personal responsibility" for the massacre. Sharon was forced to resign as Defense Minister. In 1985, Israel responded to a Palestinian terrorist attack in Cyprus by bombing the PLO headquarters in Tunisia. Israel withdrew from most of Lebanon in 1986, but maintained a borderland buffer zone in southern Lebanon until 2000, from where Israeli forces engaged in conflict with Hezbollah. The First Intifada, a Palestinian uprising against Israeli rule, broke out in 1987, with waves of uncoordinated demonstrations and violence occurring in the occupied West Bank and Gaza. Over the following six years, the Intifada became more organised and included economic and cultural measures aimed at disrupting the Israeli occupation. More than a thousand people were killed in the violence. During the 1991 Gulf War, the PLO supported Saddam Hussein and Iraqi Scud missile attacks against Israel. Despite public outrage, Israel heeded American calls to refrain from hitting back and did not participate in that war.