Although domestic terrorism has always existed in the U.S., and to varying degrees and in different manifestations in most countries, the dominant threat in the lead-up to the 9/11 attacks was thought to be from Foreign Terrorist Organizations (FTOs). The sense of menace from FTOs was heightened by the twin bombings of U.S. embassies in East Africa in 1998, and attack on the USS Cole in Yemen in 2000. While most Americans only first heard of al-Qaeda and Usama bin Laden in the days and weeks following 9/11, many in the law enforcement and intelligence communities were already very familiar with the threat posed by foreign terror groups.

In response to the catastrophic terror attacks of 9/11, the U.S. and much of the western world immediately intensified their security posture with dramatic actions ranging from the development of the U.S. Department of Homeland Security to specific target-hardening measures across the public and private sectors. Security around air travel dramatically changed with the fortification of cabin doors and more thorough screening of passengers, the number of security cameras in major cities grew exponentially, and we formally entered the era of “see something, say something.”

Read more: Homeland Security Today