16.3: Terrorism Last updated Save as PDF Page ID14590 Learning Objectives Explain why terrorism is difficult to define. List the major types of terrorism. Evaluate the law enforcement and structural-reform approaches for dealing with terrorism. The 9/11 attacks spawned an immense national security network and prompted the expenditure of more than $3 trillion on the war against terrorism. Michael Foran – 9/11 WTC 32 – CC BY-NC-SA 2.0.