What term describes a violent struggle for legitimacy among state and non-state actors?

The term that best describes a violent struggle for legitimacy among state and non-state actors is "Irregular Warfare." This form of conflict typically involves a range of unconventional tactics and strategies used by both state and non-state entities. It focuses on undermining an opponent's legitimacy and is characterized by elements such as guerrilla tactics, insurgency, and other forms of asymmetric warfare where traditional military engagements are not the primary mode of fighting.

Irregular warfare emphasizes shaping the population's perception and may involve a mix of political, social, and military efforts to gain control or influence. It reflects the complexities and nuances of modern conflict where actors may frequently operate outside established norms of traditional warfare.

In contrast, civil war typically refers to a conflict occurring within a single state, where factions compete for control; conventional warfare implies the use of regular military forces in a structured and organized manner against a similar opponent; and hybrid conflict describes a blend of conventional and irregular fighting techniques, including cyber warfare and other non-military means, but does not focus as specifically on the struggle for legitimacy.