Surprisingly, there is no precise definition of terrorism. Walter Laqueur, an expert in the field, has counted over one hundred definitions of the term. Definitions depend on one's point of view and are inherently controversial. The only general characteristic that seems to be agreed upon is that terrorism involves violence and the threat of violence. But when is the use of violence legitimate? Even the United States government does not have one, all embracing definition.
The Department of Defence, the FBI and the State Department all have different definitions of the term. This is why Walter Laqueur has written" even if there were an objective, value-free definition of terrorism, covering all its important aspects and features, it would still be rejected by some for ideological reasons." Title 22 of the United States Code ( 22 USC 2656) defines terrorism as premediated, politically motivated violence perpetrated against noncombatant targets by subnational groups or clandestine agents.
Michael Kronenwetter, in his book "Terrorism:A Guide to Events and Documents" (2004) writes that "the difficulty of defining terrorism is largely self-imposed. It is manufactured out of the need to justify certain violent actions, while condemning others." He writes that terrorist acts have three elements: "malicious actions or threats directed against people who are regarded as innocent, or who are protected by the laws and conventions of modern warfare and designed ( at least partly) to frighten, intimidate, or otherwise influence populations or governments."