Al-qaeda claimed to be behind the September 11 terrorist attack.
Senior members of al-Qaeda have also asserted responsibility for organizing the September 11 attacks.
Al-Qaeda refers to a militant Sunni Islamist multi-national organization founded in 1988 by Osama bin Laden, Abdullah Azzam, and many other Arab volunteers during the Soviet invasion of Afghanistan.
Al-Qaeda works as a network of Islamic extremists and Salafist jihadists.
The United Nations Security Council, the North Atlantic Treaty Organization (NATO), the European Union, the United States, the United Kingdom, Russia, India, labelled Al-Qaeda as a terrorist group.