Understanding the Enemy
In order to defend the homeland against terrorism as well as the other threats that plague us, we need to identify and understand exactly who these enemies are. This process is called threat analysis and is a major function of intelligence. We cannot defend everything all the time; the resources required would be prohibitive. In addition, total defense would destroy the very freedoms and way of life we are trying to protect. Therefore, we need to decide where we are most vulnerable and we can't do that until we know our enemies.
The Department of Homeland Security was supposed to create an intelligence unit that would perform threat analysis as well as a warning system to prevent surprise. This unit was supposed to be supported by the Intelligence Community (IC), which would provide the data for analysis and warning. The IC has been doing such work for many years, but it has focused on foreign enemies rather than threats to domestic security. Instead of creating its own threat analysis unit, Homeland Security has been relying on the IC-based Terrorist Threat Integration Center (TTIC) to provide the intelligence DHS needs.
Meanwhile, our enemies are at work trying to figure out ways to attack us. We already know a great deal about our adversaries and they are not just terrorists. If we are going to defend the homeland and create a vast new bureaucracy to do it, then we ought to stop the other threats to our society as well, including global organized crime, technology theft, espionage, and subversion.