Al-Qaeda was a group of fundamentalist Islam group that sought revenge from what they considered mistreatment of Arab nations at the hands of the West. They refer to a secret negotiation during World War I to keep them under British and French control.
Osama bin Laden, who led the terrorist group al-Qaeda, declared war against the United States from a hideout in Afghanistan.
With the 9/11 attack bin laden wanted America to taste the humiliation that he thought the Islamic world had been tasting for years. Then he hid in Afghanistan and Afghanistan did not hand him over to the US so the USA attacked.
