What was the rationale given for the terrorist attacks?

Answer 1

Terrorist usually wish to change the power structure of an area by violent means. The purpose being to put themselves in charge and force the populace to believe as they do.
All nations have used forms of terrorism, though they have not called it by that name.

Answer 2

Terrorist attacks are named by the side being attacked. There is no difference between an attack essentially on civilians by one side or the other, they are all terrorist attacks. The purpose is to:

• Cause infrastructure damage (roads, power water)
  
• Overload the medical care facilities
• To demoralize the civilian population
  
• To promote an image of the attackers as powerful and unstoppable
  
• To promote an image of the attackers as single minded in their pursuit of "the right"