In the aftermath of President-elect Gemayel's assassination on September 14, the IDF entered West Beirut, citing a need to prevent civil disorder. While in Beirut Israeli troops allowed the Phalangist-affiliated Lebanese Forces (LF) to enter Sabra and Shatila to root out PLO cells believed located there, hundreds of Palestinian refugees were killed in the process. This incident prompted U.S. President Ronald Reagan to organize a new Multinational Force (MNF) with France and Italy. On September 29, this new force entered Beirut, with about 1,200 troops. Their stated mission was to help the new Lebanese government and army with stability.