WTF I didn´t even wrote USA or America anywhere on my post
But anyway, as north americans are only touched when they are the subjects (something that Michael Moore cleverly explored), let´s talk about USA.
The definition of "terrorism" is the use of violence (or threat) for political/idealogical goals.
Examples of terrorism:
When USA demmanded Iraq to give their leader (Saddam Hussein) or else they would bomb the whole country (which they actually did live on tv).
When USA invaded Afghanistan and stole the power based on imaginary lies.
Now let´s think about what the pirates are doing: Taking hostages.
What would you call when more than 20 countries setup an armada to stop Somalia from interfere on what they reserved to them (stay poor, hungry, sick, being stolen and continue to serve as the world garbage). In my book this is exactly how you take a nation as hostage. You just point a gun to them and say "You are my bitch. Resist and I blow your head".