Acts of terrorism, like the famous 9/11 attack, caused the United States to do the following:
Foreign: they declared a "war on terror," mindlessly attacking anyone with a turban in the entire Middle Eastern region for 16 years and counting.
Domestic: they greatly increased security in airports, while also enacting things like the Patriot Act, which worked to strip people of their basic privacy under the "protection" (constant surveillance) of the government.
Side note: the Patriot Act has never stopped an act of domestic terrorism from occurring in the United States since its enactment.
