Terrorism-the use of violence and intimidation in the pursuit of political aims.

Terrorist-a person who uses violence in the pursuit of political arms

Justifiable force is them using it as self defense
Unjustifiable force is when they use it according to religion or politics   

2. Outside the Murrah Federal Building in Oklahoma City a car was parked outside containing a large bomb on April 19, 1995 killing 168 and injuring over 500 people when it went off the two convicted were Timothy McVeigh and Terry Nichols one received life the other received execut-ion