In order to ensure security for its citizens state must posses power. Power is prerequisite for ensuring the state to function normally and organize domestically. .
"The first move, then, for the realist is to organize power domestically" .
One cannot exercise power internationally if it has not organized power domestically. That is from the reason that if power is not organized domestically state tends to be weak and weak state will face many problems and obstacles for its survival in international system. State will eventually persist in international system if it has not power but that is only if its geo-political position and its existence is irrelevant for other states. Good example for that is the continent of Africa. It consist of many weak states that posses very small amount of power but are able to survive because of their marginal position at the world geo-political map. After it has organized power domestically state will start to compete with other states in the international system for resources, markets and influence. How successful the state will be in pursuing that goal will depend at most on the amount of power that it posses.
"What is not in question is that the basis of Morgenthau's political thought is made up of two claims. First, that "international politics, like all politics, is a struggle for power," and, second, that "politics, like society in general, is governed by objective laws that have their roots in human nature," which is defined as evil and driven by a lust for power." .
Every state tends to maximize power since power will enable state to influence other states on that way forcing them to act in the manner that this particular state wants. Since anarchy exists in International System each country is concerned for its own security. The very best way to protect itself against other states and to protect its national interest is by accumulating power and if necessary exercise it.