The 2007 Lebanon conflict began when fighting broke out between Fatah al-Islam, an Islamist militant organization, and the Lebanese Armed Forces (LAF) on May 20, 2007 in Nahr al-Bared, an UNRWA Palestinian refugee camp near Tripoli. It was the most severe internal fighting since Lebanon's 1975–90 civil war. The conflict revolved mostly around the siege of Nahr el-Bared, but minor clashes also occurred in the Ain al-Hilweh refugee camp in southern Lebanon and several terrorist bombings took place in and around Lebanon's capital, Beirut. Fighting ended in September 2007.