Isi

From 9/11 Encyclopedia:

Short for Inter-Service Intelligence, the Pakistan Secret Service. According to Abdel Monam Saidali, of the Al-aram Center for Strategic Studies in Cairo, bin Laden and the "Afghan Arabs" had been imparted "with very sophisticated types of training that was allowed to them by the CIA and ISI". The ISI, founded after WW2, was a helpful organisation during the so called Golden Crescent drug trade, which was being used to finance and equip the Bosnian Muslim Army (starting in the early 1990s) and the Kosovo Liberation Army (KLA). 

As John Cooley reports in Unholy Wars: "By 1981, when CIA chief Casey and his Saudi associates, Kamal Adhan and Prince Turki (->), were casting around for new sources of secret financing for the Afghan campaign, the bin Laden enterprises were all on a short list of possibly helpful families." In 1986, the CIA commissioned bin Laden to help build a huge tunnel complex in Khost, under the mountains near the border with Pakistan.

The CIA's aim was to provide its Afghan killers with a major arms storage depot, training facility and medical center. It was here that bin Laden decided to set up his own training camp for "Arab Afghans." He later recounted that his "volunteers were trained by Pakistani and American officers.