Definition
A major application of liberal conceptions of international security affairs is the concept of collective security , which is the formation of a broad alliance of most major actors in an international system for the purpose of jointly opposing aggression by any actor. The rationale for this approach was laid out by the philosopher Immanuel Kant in Germany over two hundred years ago. Since past treaties ending great power wars had never lasted permanently, Kant proposed a federation of the world's states. Through such a federation, Kant reasoned, the majority of states could unite to punish any one state that committed agression. This would safeguard the collective interests of all the nations together against the narrow self-interest of one nation that might otherwise profit from aggression. The success of collective security rests on two points. First, the members must keep their alliance commitments to the group. When a powerful state commits aggression against a weaker one, it often is not in the immediate interest of other powerful states to go to war over the issue. It can be very costly to suppress a determined aggressor. A second requisite for collective security is that enough members must agree on what constitutes aggression. The UN Security Council is structured so that aggression is defined by what all five permanent members, plus at least four of the other ten members, can agree on. However, this collective security does not work against a great power. When the USSR invaded Afghanistan or the United States mined the harbors of Nicargua, or France blew up the Greenpeace ship "Rainbow Warrior", the UN could do nothing because those states can veto Security Council resolutions.