Pakistan's intelligence agency the Inter-Services Intelligence (ISI) has been heavily involved in the affairs of Afghanistan since the late 1970s. During Operation Cyclone, the ISI with support and funding from the Central Intelligence Agency (CIA) in the United States recruited mujahideen militant groups on the Pakistani side of the Durand line to cross into Afghanistan's territory for missions to topple the Soviet-backed Afghan government. Afghanistan KHAD was one of two secret service agencies believed to have been conducting bombings in parts of the North West Frontier (now Khyber Pakhtunkhwa) during the early 1980s. U.S State Department blamed WAD (a KGB created Afghan secret intelligence agency) for terrorist bombings in Pakistan's cities in 1987 and 1988. It is also believed that Afghanistan's PDPA government supported leftist Al-Zulfiqar organization of Pakistan, the group accused of the 1981 hijacking of a Pakistan International Airlines plane from Karachi to Kabul.