eighteen kilometers. The new boundary enabled Jordan to expand its port facilities and established a zone in which the two parties agreed to share petroleum revenues equally if oil were discovered. The agreement also protected the pasturage and watering rights of nomadic tribes inside the exchanged territories. Jordan signed a mutual defense pact in May 1967 with Egypt, and it participated, along with Syria, Egypt, and Iraq in the Six-Day War of June 1967 against Israel. During the war, Israel took control of East Jerusalem and West Bank, leading to another major influx of Palestinian refugees into Jordan. Its Palestinian refugee population—700,000 in 1966—grew by another 300,000 from the West Bank. The result of the 29 August 1967 Arab League summit was the Khartoum Resolution, which according to Abd al Azim Ramadan, left only one option -a war with Israel. The period following the 1967 war saw an upsurge in the power and importance of Palestinian militants (fedayeen) in Jordan. Other Arab governments attempted to work out a peaceful solution, but by September 1970, known as the Black September in Jordan, continuing fedayeen actions in Jordan — including the destruction of three international airliners hijacked and held in the desert east of Amman — prompted the Jordanian government to take action. In the ensuing heavy fighting, a Syrian tank force took up positions in northern Jordan to support the fedayeen but was forced to retreat. By September 22, Arab foreign ministers meeting at Cairo had arranged a cease-fire beginning the following day. Sporadic violence continued, however, until Jordanian forces won a decisive victory over the fedayeen in July 1971, expelling them from the country. An attempted military coup was thwarted in 1972. No fighting occurred along the 1967 cease-fire line during the Yom Kippur War in 1973, but Jordan sent a brigade to Syria to fight Israeli units on Syrian territory. In 1974, King Hussein recognised the PLO as the sole legitimate representative of the Palestinian people. However, in 1986, Hussein severed political links with the PLO and ordered its main offices to be closed. In 1988, Jordan renounced all claims to the West Bank but retained an administrative role pending a final settlement. Hussein also publicly backed the Palestinian uprising, or First Intifada, against Israeli rule. Jordan witnessed some of the most severe protests and social upheavals in its history during the 1980s, protests in Jordanian universities especially Yarmouk