“Terror’s Mask: Insurgency within Islam” by Michael Vlahos. Joint Warfare Analysis Dept, Applied Physics Laboratory, Johns Hopkins University
Terror is a tactic used successfully by states and groups alike.
Its essence is violence to civilians; any weapon qualifies.
The threat of terrorist attacks is as much terrorism as the attacks themselves. (The object of terrorism is to instil terror.)
Nuclear weapons are useful for little else; states that own them are ipso facto terrorist. That includes the United States, the United Kingdom, Russia, China, Israel, Pakistan, and India.