The 2003 US invasion of Iraq became the largest, longest and most costly use of armed force since the war of Vietnam. This is the first major post-Cold War U.S. military action undertaken unilaterally, without an international coalition, and the United States' first experience as an occupying power in a Middle Eastern country. Although the decision to invade was peculiar (US military connection to an Arab or Muslim country), the thesis here is that the Iraqi invasion had to do with motivations related to natural security, power and resources. Both realism and neoconservatism claim to grasp the reasons for the war, but only through a global comparison between the two can a synthesis be achieved. On March 20, 2003, the United States Army invaded Iraq in a ground campaign that lasted nearly three months. . According to the then President of the United States, George W. Bush, and the then Prime Minister of the United Kingdom, Tony Blair, the stated reasons for the invasion included the disarmament of Iraq, especially with regards to weapons of mass destruction ; the end of Saddam Hussein's support for terrorism; and the liberation of the Iraqi people” (White House Archives). On May 1, the end of major combat operations was declared, ending the invasion period and beginning the military occupation period. However, was this war really necessary to put an end to Saddam Hussein's regime in Iraq – a regime that, at the time, had been considered a threat to the United States, as neoconservatives claim? Furthermore, did Iraq really possess weapons of mass destruction, or was control of Iraqi oil the reason the United States invaded, as realists might surmise? Often defined as the “pessimistic vision” of international politics… at the center of document ......ospect.org/cs/articles?article=the_road_to_aqaba>.Lieberfeld, Daniel. "THEORIES OF CONFLICT AND WAR IN IRAQ". International Journal of Peace Studies 10.2 (2005): 1-20. Print.Lowbeer-Lewis, Nathaniel. "A neoworld? NEOCONSERVATISM, INTERNATIONAL RELATIONS AND THE WAR IN IRAQ." Diplomatic and International Canada 2009: 72-75. Diplomat and international Canada. 2009. Network. December 4, 2010. “President Discusses Start of Operation Iraqi Freedom.” White House Archives. 22 March 2003. Web. 4 December 2010. whitehouse.archives.gov/news/releases/2003/03/20030322.html>. Walt, Stefano. “International Relations: One World, Many Theories.” Foreign policy. Spring 1998: page. 29-45.Waltz, Kenneth. “The anarchic structure of world politics” International politics. New York: Pearson, 2009. 37-58.