The nature and form of international relations are primarily conditioned by the inequality of states arising from the political division of unique natural resources used for the survival and development of societies. The concept of structural power has been developed within the field of international political economy. John G. Stoessinger maintains that power in international relations is 'a nation's ability to use its tangible and intangible resources in such a way as to affect the behaviour of other nations'. Henry A. Kissinger distinguishes between offensive power, defensive power and deterrent power. The concept of structural power has been developed within the field of international political economy. As in domestic relations, actors in international relations most often have unequal powers or powers frequently perceived as unequal. Research to date identified several types of action by actors in international relations and these were more or less analysed in detail and described as the manifest forms of power in those relations.