were trained in “bomb-making, sabotage and urban guerrilla warfare” in Afghan camps that the CIA helped set up

"What is less often emphasized is the infrastructure established during the Afghan Jihad by the ISI, Pakistan’s intelligence agency, with US and Saudi funding, which produced thousands of militants. According to an estimate by US officials, some fifteen thousand fighters were trained in “bomb-making, sabotage and urban guerrilla warfare” in Afghan camps that the CIA helped set up." (thanks Amir)