In general, the international regime succeeds in keeping the world safe from the risk of attack with weapons of mass destruction (WMD). After the war on terrorism, no country suffers attacks from weapons of mass destruction. However, the existence of weapons of mass destruction still constitutes a potential risk and should not be overlooked. In the following paragraph, the concept of security, issues of proliferation of conventional and nuclear weapons and the function of the international regime will be mentioned. Change in the concept of “Security” Characteristics of the new concept of security (200) Old concept of security Before the war against terrorism, the concept of security is still traditional. It refers to the security of the monopoly of violence. The condition for the survival of a state is that it has the power to maintain an effective monopoly on the use or authorization of violence on its territory. The great powers believe that internal conflict is not possible. Conflicts between states within the international system are quite common. In other words, security is a concept of protecting independent sovereignty and territorial integrity. It's related to internal affairs. It is linked to the survival of the State. Usually, conventional warfare will be used as a means of maintaining security when there is no peaceful way to achieve the goal (Chung, 2013). New concept of security After the war on terrorism, the concept of security is not only about maintaining independent sovereignty and territorial integrity. but also protect the food, health, money and commerce systems within society. This is linked to the attacks of September 11, 2001. A small group of terrorists launched a suicide attack by hijacking a civilian plane as a weapon to strike the world-class financial center and the Pentagon. More than three thousand people died (BBC, 2001). The world is in the middle of paper and it is forbidden to export nuclear weapons or techniques to non-nuclear countries, while non-nuclear countries must guarantee that they will not seek to acquire nuclear weapons. Nuclear disarmament will be implemented everywhere in the world (UN, 2014). Above all, international regimes are believed to protect the world from the risk of weapons of mass destruction. These years, no country uses weapons of mass destruction in conventional war. However, the international regime that allows the possibility of attacks with weapons of mass destruction still has certain limits. For example, the NPT Treaty does not provide for any sanctions against those who violate the treaty. Treaty commitment is not guaranteed (Chung, 2013). Furthermore, the response of the international regime is still concentrated at the state level. Little effort is being made to eliminate the clandestine market for nuclear weapons. This means that the risk cannot be completely eliminated. Therefore, great efforts are required to permanently resolve the issue..