Pierre Tristam, Editor and Publisher of the non-profit news organization Flaglerlive.com, wrote in his article "'Black September': The Jordanian-PLO Civil War of 1970" on About.com (accessed Jan. 26, 2012):
"The Jordanian civil war of September 1970, also known in the Arab world as Black September, was an attempt by the Palestine Liberation Organization (PLO) and the more radical Popular Front for the Liberation of Palestine to topple Jordanian King Hussein and seize control of the country. The PFLP sparked the war when it hijacked four jetliners, diverted three of them to a Jordanian air strip, blew them up, and for three weeks held on to dozens of the 421 hostages it seized as human bargaining chips... Even though [PLO leader Yasser] Arafat worked for the release of the hostages, he also turned his PLO militants loose on the Jordanian monarchy. A bloodbath ensued.
Up to 15,000 Palestinian militants and civilians were killed, swaths of Palestinian towns and refugee camps, where the PLO had massed weapons, leveled, the PLO leadership decimated, and between 50,000 and 100,000 people were left homeless. Arab regimes criticized Hussein for what they called 'overkill.' Before the war, Palestinians had run a state-within-a-state in Jordan headquartered in Amman. Their militias ruled the streets and imposed brutal and arbitrary discipline with impunity. Hussein ended the Palestinians' reign...
On Sept. 25, 1970, Hussein and the PLO sign a cease-fire mediated by Arab nations... Arafat and the PLO were expelled from Jordan by early 1971...
...[T]he Jordanian-Palestinian war of 1970 led to the creation of the Palestinian Black September movement, a commando faction that broke away from the PLO and directed several terrorist plots to avenge Palestinians' losses in Jordan, including hijackings, the assassination of the Jordanian prime minister, Wasif al-Tel, in Cairo on Nov. 28, 1971, and, most notoriously, the murder of 11 Israeli athletes at the 1972 Munich Olympics.
Israel, in turn, unleashed its own operation against Black September as Israeli prime Minister Golda Meir ordered the creation of a hit squad that fanned out in Europe and the Middle East and assassinated numerous Palestinian and Arab operatives."
Ian J. Bickerton, PhD, Associate Professor of Middle Eastern and United States History at the University of New South Wales-Australia, and Carla L. Klausner, PhD, Professor of Modern Middle East, Medieval Europe and Judaic Studies at the University of Missouri-Kansas City, in their 2002 book A Concise History of the Arab-Israeli Conflict, wrote:
"In Jordan, the PLO became a serious threat to political stability. It prevented King Hussein from considering any negotiated settlement with Israel that did not include the PLO; it invited Israeli retaliation for its activities; and both indirectly and directly it undermined the monarchy through the PLO covenant's avowed intention to liberate all of mandatory Palestine [which originally included Jordan] and the leftists' death threats against the U.S. supported king. Palestinian anger intensified when Hussein seemed receptive to a plan of U.S. Secretary of State William Rogers in June 1970 [during the war of Attrition] that called for Israeli withdrawal from the occupied territories in return for recognition of the Jewish state.
The PLO became so much like a state within a state in Jordan that eventually there was a showdown with [King] Hussein [of Jordan]. This occurred after Palestinians hijacked three airplanes to Amman (Jordan's capital) in September 1970 and subsequently blew them up on the ground, making the king appear impotent. After bloody confrontations between the Jordanian army and Palestinian commandos, in which around 3,000 Palestinian fedayeen [guerrilla fighters] were killed, and the Jordanians turned back Syrian tanks, Hussein reasserted his control. He could not have succeeded, however, without the support of Israel, which, at the request of the United States, had threatened to intervene to prevent Syrian success. At that time, the Syrian Air Force commander was Hafez al-Assad, later Syria's president, who was afraid of Israeli-U.S. intervention and refused to provide air cover for the Syrian tanks. By July 1971, Hussein had expelled PLO terrorists and fighters from Jordanian territory...
Following the showdown with Jordan's King Hussein in 1970 and 1971, and their expulsion from Jordan, the PLO leaders and many PLO fighters, eventually numbering 15,000, moved to Lebanon, joining the by now 200,000 or more Palestinian refugees already there living in camps. The PLO established bases and began to organize the refugees in the camps. They also began to dominate the Shiite areas of southern Lebanon. Israeli retaliatory strikes against refugee camps and into southern Lebanon began to affect the Shiites in the south, who also came to resent the Palestinian presence. Many of them began to migrate to the north, where they would eventually organize politically and become a significant new political factor in Lebanese politics.
With Lebanon being drawn increasingly into the Palestinian-Israeli situation, tension grew between those attempting to maintain Lebanese 'sovereignty' and those, especially among the Muslims, who supported the Arab and Palestinian cause against Israel and supported the activities of the PLO. Thus, the Palestinian issue exacerbated already tense economic and political differences. These differences exploded again into civil war in 1975."
Thomas L. Friedman, MA, New York Times foreign affairs columnist, in his 1989 book From Beirut to Jerusalem, wrote:
"The PLO [Palestine Liberation Organization] guerrilla groups were granted significant economic aid by the Arab states in order to carry on the battle with Israel, while they watched from the sidelines. The PLO used this support and political backing to take control of Palestinian refugee camps in the weaker Arab countries, particularly Lebanon and Jordan, and to use those camps as bases of operation against targets in Israel and against Israeli targets abroad. In both Jordan and southern Lebanon, the Palestinian guerrillas assumed quasi-sovereign authority over certain regions bordering on Israel. Their raids on Israel brought about Israeli retaliations, which created tensions between the Palestinians and Lebanese and Palestinians and Jordanians...
Matters came to a head in Jordan in September 1970, when radical Palestinian guerrillas brought to Jordan three hijacked airliners [a Pan Am and TWA from Germany and a Swissair from Switzerland] and prevented the Jordanian army from getting near the planes or rescuing the passengers. Recognizing that he was on the verge of losing control over his whole kingdom, King Hussein decided to wipe out Arafat and his men once and for all by launching a full-scale offensive against the PLO-dominated Palestinian refugee camps and neighborhoods in the Jordanian capital, Amman. The PLO guerrillas responded by calling for Hussein's overthrow and vowing to wrest Jordan from his hands. In the end, King Hussein, who was supported by both Jordan's Bedouin-dominated army and many East Bank Palestinians who appreciated the order and prosperity the King had brought to their lives, prevailed. Arafat was forced to flee Amman disguised as an Arab woman..."