Complex Interdependence is a theory which stresses the complex ways in which as a result of growing ties, the transnational actors become mutually dependent, vulnerable to each other’s actions and sensitive to each other’s needs.

Robert O Keohane and Joseph S. Nye in their book ‘Power and Interdependence: World Politics in Transition’, described three main characteristics of Complex Interdependence: -

1. Multiple Channels: In international politics there are multiple channels connecting the societies, including all the interstate, transgovernmental, and transnational transactions.
2. Absence of Hierarchy Among Issues: In the world of Complex interdependence, there is no hierarchy among the issues. The dividing line between domestic and foreign policy becomes blurred and there is no clear agenda in interstate relations. There are multiple issues which are not arranged in a clear or consistent hierarchy. Among other things, “military security does not consistently dominate the agenda.”
3. Minor Role of Military Force: As opposed to the central role that force is given in realist’s world, i.e. an ultimate necessity to guarantee survival, Complex Interdependence assumes that in international relations force is of low salience. When Complex Interdependence prevails, military force could be irrelevant in resolving disagreements on economic issues among members of an alliance, however simultaneously be very important for the alliance’s political and military relations with its rival bloc. According to Keohane and Nye, intense relationships of mutual influence may exist but force is no more considered an appropriate way of achieving other goals such as economic and ecological welfare which are becoming more important, because mostly the effects of military force are very costly and uncertain.

Keohane and Nye do not claim that military power is insignificant. They argue that military actions are costly and these costs have increased for a number of reasons. For example, nuclear weapons increase the costs associated with conflict. In addition, using force on one issue could have negative effects on other economic goals. Thus, relative to cost there is no guarantee that military means will be more effective than economic ones to achieve a certain goal. Keohane and Nye explained such a cost with four main explanations: There is a risk of nuclear escalation, negative effects on achievement of economic goals, domestic opposition to the human costs in the case of war and peoples resistance in weak countries. Also Keohane and Nye stresses that transnational actors would seek their own goals rather than a state based desire. Consequently, international organizations would play significant role on setting the security agendas as also be voice of the weaker states.