On September 1st, President Reagan announced a new peace initiative between Israel and the Palestinians, that included a freeze on new settlements, limited autonomy for Palestinians in the West Bank and Gaza, and some version of a "Jordanian solution," plus lots of new economic and military aid for Israel. But Israel rejected the Reagan plan, and the initiative remained stalled; in the West Bank, Israel immediately launched several new settlements. At the same time, Israel was having even more difficulties with the new president of Lebanon, Bashir Gemayel. Tel Aviv had expected Gemayel to be "their man" in Beirut, but unexpectedly Gemayel was emerging as a Lebanese nationalist instead.
On September 11th, two weeks before the end of their official mandate, the last U.S. Marines were withdrawn from Beirut. Three days later, Gemayel was assassinated. Within hours, Israel responded by invading the Muslim- (and formerly Palestinian-) dominated West Beirut. It was in complete violation of the guarantees of protection that were the basis for the agreement the U.S. had negotiated with the PLO. After a few hours, Defense Minister Sharon announced that the Christian Phalangists, the most anti-Palestinian of all the Christian militias, would actually enter the Palestinian camps, rather than the Israelis themselves. The senior Israeli commander met with the top Phalangist leaders and told them, he said, "to act humanely, and not to harm women, children and old people."
On Thursday, September 16, Israeli troops lit flares to light the way for their Phalangist allies to enter the Sabra and Shatila refugee camps, on the outskirts of West Beirut. The massacre of unarmed children, women and old men went on for three days. It resulted in the deaths of between 2,000 and 3,000 Palestinians, most of them left piled up or hastily buried in mass graves. The Red Cross later said it would be impossible to know the exact number who died.
There was no question that the Israeli soldiers knew what was going on inside—it was visible even without their high-powered binoculars, and the sound of machine-gun fire continued throughout the days and nights. Finally the U.S. pushed Israel to withdraw the Phalangists. The Los Angeles Times reported that U.S. Special Envoy Morris Draper told the Israeli officers that "you must stop the massacres. They are obscene. I have an officer in the camp counting the bodies. ...They are killing children. You are in absolute control of the area and therefore responsible for that area."
Israel would remain occupying a strip of south Lebanon until 2000, when the mounting deaths and injuries of young Israeli soldiers at the hands of Hizbullah resistance forces brought about a political outcry inside Israel. The occupation was finally ended unilaterally, implementing most of the requirements of resolution 425 twenty-two years after it was passed.