This essay is interested in addressing the argument made by "liberal idealists" in the interwar period about the prospects of designing international institutions to reduce or eliminate the probability of war . The essay will discuss the failure of the League of Nations in maintaining international peace and security; and how this led the Allied Powers of World War II to work towards the creation of an international institution that would be more efficient and powerful in establishing international peace and security. The result was the creation of the United Nations (UN) in 1945, which has demonstrated remarkable success in maintaining peace and security while promoting international cooperation. Yet, as the examples included in the essay demonstrate, even the United Nations has failed to stop all wars. The roles of other multilateral organizations such as the WTO, EU and ASEAN in promoting peace will also be discussed. The theory of liberalism was popular in the 1970s, when scholars argued that realism in international relations was obsolete. Liberals argued that there were no strictly national interests, because nation states had to consider their own interests as part of regional and even global interests. Therefore, importance has been given to the role of multinational cooperation – witness the rise of such organizations after the formation of the United Nations – EU, WTO, ASEAN are just a few examples, mostly based on economic cooperation with an emphasis on regional economic cooperation. As these organizations became successful, they covered more countries that saw the benefits of belonging to them and expanded their cooperation from strictly economic matters to more sovereign matters. The EU's single currency is a great example of this. Nations were willing to give up some of their money without first having a credible replacement. This has destabilized the region and we are now suffering the consequences. Ultimately, such events also call into question the effectiveness of the United Nations. The pendulum swings towards realism once again. As powerful countries like the United States, and countries that have powerful backers like Israel and rogue states like North Korea, flaunt UN regulations and get away with it, there is a danger that the world will once again face the dangers of total war. This time the only thing preventing an all-out war is the fear of mutually assured destruction, the fear that one's adversary also has the ultimate weapon: nuclear energy. Liberal ideas of globalization and interconnectedness through multilateral organizations can diminish the threat of war. , but realistically the threat of war will never be eliminated.