The PLO suffered a major reversal with the Jordanian assault on its armed groups, in the events known as Black September in 1970. The Palestinian groups were expelled from Jordan, and during the 1970s, the PLO was effectively an umbrella group of eight organizations headquartered in Damascus and Beirut, all devoted to armed struggle against Zionism or Israeli occupation, using methods which included direct clashing and guerrilla warfare against Israel. After Black September, the Cairo Agreement led the PLO to establish itself in Lebanon.