There are different theories as to the role of international organizations in maintaining peace and security. Accordingly, constructivists argue that international organizations induce states to cooperate internationally even though their power and utility-maximizing interest is not achieved. Neo-Liberals also believe that international organizations are vital to make the world peaceful and cooperative. Neo-realists, on the other hand, argue that international organizations are the means by which states achieve their self-interest, thus, contribute nothing for peace and security. UN, as a testing ground, has contributed a lot in the maintenance of peace and security by deploying peace-keeping forces in the conflict areas though still lack of member states’ commitment to provide necessary supports, the level of their interest at stake and the interest of veto powers put challenges on the effective operation of the organization.