Who is the enemy?

Regardless of what you think about the "war on terror", it is interesting to note that most US citizens might not know what to actually call our enemy. In WWII we certainly knew that we were fighting the Nazis, the fascist Italians and Imperial Japan. Ex Senator Rick Santorum wrote this exceptional article for the Philadelphia Inquirer that discusses the current lack of knowledge as to exactly who and what we are fighting for.
http://www.philly.com/inquirer/opinion/18757289.html