At the same time though, the arrival of civilian refugees went along with an increasingly strong presence of Palestinian Militants. Thus, clashes between Palestinians and Israel increased dramatically: On 12 May 1970, the IDF launched a number of attacks in South Lebanon, including Tyre. The Palestinian insurgency in South Lebanon escalated further after the conflict of Black September 1970 between the Jordanian Armed Forces (JAF) and the Palestine Liberation Organization (PLO). The PLO leadership under Yasir Arafat relocated to Lebanon, where it essentially created a state within a state and recruited young fighters - known as "fedayeen" - in the refugee camps.