Homeland Security

Homeland security as a domestic defense strategy became a national priority after the September 11, 2001, attacks on the World Trade Center in New York City, the Pentagon in northern Virginia, and United Airlines Flight 93 that crashed in Pennsylvania. The attacks, conducted by the terrorist group, al Qaeda, resulted in nearly 3,000 deaths, including 343 firefighters and 60 police officers who responded to the attacks. Those attacks led to changes in how government bodies in the United States respond to terrorist threats.

The attacks and the new emphasis on homeland security resulted in changes in government at all levels, particularly the federal government. It created new thinking in the Department of Defense. Rather than focusing primarily on traditional warfare involving wars with nation-states, the U.S. ...