Initially, the Israelis refused to let the MNF deploy until the PLO left, instead intensifying their attacks on Beirut. The PLO completed its withdrawal by September 1. Though the MNF was supposed to remain for thirty days, Weinberger announced that the Marines would leave on September 10. On September 14, Lebanese President-elect Bashir Gemayel, whose election had been backed by the Israelis, was assassinated. Citing a need to prevent civil disorder, the IDF entered West Beirut. By September 18, it became clear that the Israelis had allowed Maronite militiamen to enter the Sabra and Shatilla camps and massacre Palestinian civilians.
