Contemporary international relations are governed by the rule of peaceful coexistence of states. Accordingly, armed aggression is prohibited by international law. This is soundly confirmed by Art. 2 par 4 of the Charter of the United Nations stating that “All Members shall refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the Purposes of the United Nations”. Violation of this obligation is followed by arising of the aggressor’s responsibility, not only towards the state directly affected, but also towards the whole international community. It happens like that because prohibition of aggressive war is of ius cogens character, as it was established in the interest and on behalf of all international law subjects. Consequences of an aggression act are incomparably greater than those waiting for an ordinary tortfeasor. In addition to traditional forms of responsibility, such as restitution, monetary compensation, or satisfaction, international law developed a wide range of other remedies applied against an aggressor.