This led the PLO to intensify its bombardments in the north forcing thousands of Israelis to move south. The United States negotiated a cease-fire which resulted in relative calm on the northern border until June of 1982.
In June of 1982, a Palestinian terrorist attempted to assassinate the Israeli Ambassador to the UK, Shlomo Argov, leaving him in a coma and paralyzed until his death in 2003. The PLO found loopholes in the cease-fire agreement and launched many attacks from the Jordanian border into Israel.
In response, Israel launched a series of air raids against the PLO and attempted to push back the terrorist forces 40 km from the border. At the same time, Syria was taking advantage of the lawlessness in Southern Lebanon and the complacency of UNIFIL forces to intervene and so, they sent their own forces to establish a strong presence in southern Lebanon. Many Palestinian-Arab allied forces were being deployed and ready for battle.
To counter the buildup, Israel launched air strikes which began the First Lebanon War. The Israelis, as planned, pushed the Syrian and Palestinian forces north. The Israelis advanced towards the village of Sil where after three battles, a path to Beirut was cleared. To prevent Israel from entering Beirut, the PLO accepted the United Nations' ceasefire, however, they had no interest in honoring it. Instead, the PLO terrorists in the areas leading towards the Lebanese Capital brazenly violated the agreement, although Israel and the UN were prepared for this. The failure of the ceasefire led to the increase of Israeli forces in these areas to boost the chances of success in capturing Beirut. It took the Israelis to successfully conquer Beirut before the Syrian and PLO forces realized they had no chance to succeed and they retreated.
After one month of warfare, The Palestinian terrorists and Syrian forces evacuated from Beirut. The Palestinian terrorists were taken in by several Arab nations while the Syrian forces retreated to the Bekaa Valley region of Syria. In September, 8 Israelis were kidnapped while at an observation post in the Hamdoun region in Lebanon. In 1983, 6 of the hostages were handed back to Israel in exchange for 4,700 terrorists detained in Ansar camp in Lebanon.