The September 11 attacks transformed the first term of President George W. Bush and led to what he has called the Global War on Terrorism . The accuracy of describing it as a " war " and its political motivations and consequences are the topic of strenuous debate . The U.S. government increased military operations , economic measures and political pressure on groups which it accused of being terrorists , as well as increasing pressure on governments and countries which it accused of sheltering them . October 2001 saw the first military action initiated by the US . Under this policy , the NATO invaded Afghanistan in order to remove the Taliban regime ( which harbored al-Qaeda ) and capture al-Qaeda forces
September 11 attacks
September 11 attacks
Aftermath of the September 11 attacks