The Palestine Liberation Organization (PLO) was based in Lebanon for a significant period of time (1960s-1982), using their set-up in the country to expand as an organization, gathering support and maintaining their armed struggle with Israel. Arguably, the Lebanon period was the most significant time in the PLO's existence, both for reasons of political gain and international recognition – though it also involved a great deal of violence, displacement of civilians and economic instability. The PLO was able to maintain a strong presence, particularly in Southern Lebanon for a number of years and at times was able to have a positive impact on the local population, but due to religious tensions and a confusion of structure was often the cause of dissatisfaction and fear amongst Lebanese citizens. Late 1960s–1982 The origins of the PLO's presence in Lebanon goes right back to the late 1960s, following the 1967 Six-Day War. There were already large areas of Lebanon populated by Palestinian exile communities, or around 12% of the total population. Lebanese president Charles Helou was anxious about the prospect of nationalist sentiment causing turbulence in Lebanon following the war, which had ignited mass support from Arab communities of the Palestinian cause. Nevertheless, guerrilla networks were increasingly active throughout the late 1960s and were given even more freedom after the Cairo agreement in 1969, in which refugee camps in Lebanon were placed under the command of Palestinian forces, instead of the heavy-handed Deuxième Bureau. The establishment of the PLO as being based wholly in Lebanon came after king Hussein of Jordan's decision to expel the group from his country in 1970. The Black September movement which formed as the result of the hijacking of planes, which were brought into Jordan. Much of 1970s Lebanon exists in history under the shadow of the lead-up to and subsequent bloody realization of the civil war, which the PLO became embroiled in after initial reluctance of any involvement. It was not in the interests of the PLO to get involved in a conflict which would drain resources and detract focus from the goal of planning insurgencies against Israel. The end of the PLO's time in Lebanon came abruptly and decisively after Israeli forces invaded Southern Lebanon and forced PLO forces out of the country. As a result of this, the organization had to move its base to Tunis, Tunisia. The camps: autonomy and a state within a