The US made several policy changes to combat terrorism following the 9/11 attacks. Most notably, it created the Department of Homeland Security, increased airport security, and went to war in Afghanistan.
In the two decades since the attack, there were far fewer terrorist acts on US soil and most attacks aren’t lethal, according to data from the National Consortium for the Study of Terrorism and Responses to Terrorism (START). The consortium is a Department of Homeland Security science and technology center.
