(IANAL, and these questions are meant only to incite thought or details (if anyone has any))
Is the state of being a terrorist the act of terrorizing or the thought of doing something that is terrorizing? If it's the latter, how is that different than a thought crime? Even if it's planned, but never executed, is one a terrorist? How does one distinguish between having planned but never intending to execute vs having planned but didn't get around to execute? Is a plan that is never executed a failed plan? There is a distinction between "murder" and "conspiracy to commit murder", the former being the act and the latter being participation in the planning.
If the actor attempts to terrorize and no one is actually terrorized, has an act of terrorism been committed?
If a program is designed, but never written, is it software? If a program is written, but never executed, is it software?