The United States Code, Title 22, Chapter 38, Section 2656f(d)(2) defines terrorism as: “Premeditated, politically motivated violence perpetrated against noncombatant targets by sub-national groups or clandestine agents.”
Terrorism, then, is the use of force or violence against persons or property in violation of the criminal laws of the United States for purposes of intimidation, coercion, or ransom.
Terrorists use threats to create fear among the public in an effort to convince them that their government is powerless to stop acts of terrorism. It is also a way for the terrorists to get publicity for their causes.