Three-quarters of the 1,000 or more Stinger missiles, given by the CIA to the Islamic mujaheddin rebels to assist their "democratic opposition" during Afghanistan's civil war, are unaccounted for. The shoulder-held missiles are guided by a system that homes in on the heat of a jet engine from a range of almost five kilometres, and can easily result in the destruction of passenger jets. Not one could be recovered when the USA afterwards tried to reclaim the unused missiles, on a buy-back arrangement using a special $10 million emergency fund. It is believed the Afghan rebels sold them elsewhere (the missiles could be acquired at exhorbitantly swollen prices in neighbouring Pakistan). Some were known to have been acquired by Iranians.