Blowback , or unintended consequences of funding the mujahideen , was said to have come to the United States in the 1993 World Trade Center bombing and the September 11 attacks . In the 1993 bombing , all of the participants in the bombing " either had served in Afghanistan or were linked to a Brooklyn-based fund-raising organ for the Afghan jihad " that was later " revealed to be al-Qaeda 's de facto U.S. headquarters " . Principals in the 2001 attack — Osama Bin Laden , Khalid Sheikh Mohammed — had both fought in Afghanistan , and bin Laden was a lieutenant of Abdullah Azzam . His group al-Qaeda , returned to Afghanistan to take refuge with the Taliban after being expelled from Sudan . Before the 9/11 attack , al-Qaeda had bombed two U.S. embassies in Africa in 1998 , and nearly sank the USS '' Cole '' in Yemen in 2000 . However , no direct U.S. aid to bin Laden or any of his affiliates has ever been established
1993 World Trade Center bombing
1993 World Trade Center bombing
Soviet–Afghan War