Why did Jordan expel the PLO in 1970?
Following the June 1967 Six Day War, the Palestine Liberation Organization (PLO) established its major base of operations for the war against Israel in Jordan. Throughout the late 1960s, a cycle of Palestinian guerrilla attacks followed by Israeli retaliatory raids against Jordan caused much damage to Jordan and put major strain on Jordan’s relationship with the US and other Western countries. By 1970, it was widely believed that PLO leader Yasser Arafat and other factional heads were attempting to overthrow King Hussein, who viewed their operations against Israel as a threat to Jordan.
By 1970, Palestinians, both Jordanian citizens and refugees, were almost as numerous in Jordan as King Hussein's own Bedouins. Arafat used the estimated 20,000 Palestine Liberation Organization fighters in Jordan to exercise control over much of the Palestinian population. In many parts of the country, he was the de facto government. Jordan was seen as a waystation toward defeat of Israel and a united Palestinian Arab state encompassing Israel and Jordan. As many Palestinian Arabs put it: "the road to Tel Aviv lies through Amman".
On September 6, 1970 militant factions of the PLO hijacked four foreign planes. They flew three to Dawson's Field in PLO-controlled northern Jordan and one to Cairo. European governments secured the release of the hostage passangers by agreeing to release PLO terrorists from their prisons. The PLO then blew up the planes.
King Hussein decided it was time to act. Throughout September the Jordanian military launched attacks to push the PLO out of Jordan, attacks now called "Black September" by the PLO. Casualty reports are uncertain, but hundreds or perhaps thousands of PLO fadayeen were killed in the fighting and large numbers of Palestinian Arab civilians died as well. Arafat retreated to northern Jordan, close to his Syrian sponsors. Within 10 months the PLO were driven out of Jordan completely, and re-established themselves in Lebanon, a choice that led to eventual disaster for Lebanon.
Jordan's attack on the PLO led to an escalation of Syrian-Israeli tensions. The wider Arab world, which had long distrusted Hussein as a Western puppet, sided with the PLO. Syria sent tanks into Jordan -- and the king was powerless to stop their steady advance. After Hussein sought American intervention, four Israeli Phantom jets flew low over the Syrian tanks. Without a shot being fired, the tanks turned north and headed back toward Damascus. Israeli troops were also deployed along the Jordan River. These actions were seen in Washington as having deterred a large-scale Syrian invasion of Jordan. As a result, US President Richard M. Nixon increasingly viewed Israel as an important strategic asset, and the Rogers Plan was allowed to die.