 However, China's strategic force unable of projecting power beyond its region and its nuclear arsenal of 250 warheads (compared to 7700 of the United States) mean that the unipolarity will persist in the policy-relevant future.Several theories of international relations draw upon the idea of polarity.The balance of power was a concept prevalent in Europe prior to the First World War, the thought being that by balancing power blocs it would create stability and prevent war.