War is defined by the use of armed force and is a violent conflict of interests between or among organized organizations. These groups have traditionally been established nation-states, but they may also include any nonstate organization with its own political objectives and the capacity to incite organized violence on a large enough scale to have significant political repercussions, such as an international coalition or a faction inside or outside of an existing state.
A violent battle between two opposing, autonomous, and incompatible wills that are each attempting to force themselves on the other is the core of war. Fundamentally, war is a social interaction. Clausewitz referred to it as a Zweikampf, or "twostruggle," and proposed the analogy of two wrestlers locked in a hold, each applying force and counterforce to attempt to free themselves.