Despite a peace deal brokered with its Arab neighbor Egypt, Israel's northern border with Lebanon remained a major trouble spot.

The Palestinian Liberation Organization, which had been founded in 1964 in Beirut, continued to use Lebanon as its main base of operations against Israel. By the early 1970s, attacks and counterattacks by the PLO across the border prompted Israel to launch an invasion of southern Lebanon in 1978. The United Nations reached an agreement for Israel to withdraw and an international peacekeeping unit to monitor the area.

By June 1982, Israel viewed the Syrian and PLO presence in southern Lebanon as a threat and attacked. Yasser Arafat and PLO followers were forced to evacuate Beirut strongholds and later reestablished their headquarters in Tunisia. With the help of U.S. envoy Philip Habib, the international community in August negotiated the PLO withdrawal agreement and deployed U.S., French, and Italian forces to Beirut to facilitate the move.

Civil war and violence continued to rage in Lebanon and key political figure, president-elect Bachir Gemayel was assassinated before he could even take office. The turmoil and the continued presence of PLO fighters prompted a second Israeli invasion in September 1982. This time Israeli forces moved all the way up to the capital of Beirut, occupying the western half of the city.

As the U.S. worked to find a settlement to the Lebanon situation, Islamic extremists began to target American diplomats and troops. In April, a series of suicide bombings hit the U.S. and French embassies, killing more than 100. Despite the violence, the U.S. mediated an Israel-Lebanon peace and withdrawal agreement in May. Israeli forces began to leave Lebanon, but the violence did not end. In October of 1983, a suicide car bomber destroyed the U.S. Marine barracks in Beirut, 241 were killed and hundreds more injured. Much of the international community pulled out of Lebanon within six months, including the U.S. in February.

Syria refused to recognize the agreement and left about 40,000 troops in northern Lebanon. Israel responded by maintaining control over a 12-mile-wide "security zone" in southern Lebanon.

The Hezbollah, an Islamic militant group that opposes Israel's presence in Lebanon, continued to attack military posts in southern Lebanon and northern Israel. Israeli forces continued to combat these forces for another 22 years until Israel left southern Lebanon in January of 2000.