This thesis is a study of US foreign policy that aims at ousting the Baath regime and to eliminate its leader,Saddam Hussein from the region,as a way of balancing the growing power of Iraq in the region.Three major claims of this thesis include:(1)US foreign policy that calls for such action as preemption is consistent with unilateralism and hegemonic realism(2)the U.S invasion of Iraq is characterized as illegitimate and(3)it has unprecedented consequences,thus regarded as a failed policy.　　The2003Iraq war represents the biggest and most expensive post-cold war military expeditions unilaterally undertaken by the U.S devoid of United Nations approval and the first experience of U.S as an occupying power in the Arabian Gulf.It was a U.S singular decision complimented by the"Coalition of the willing"(members of the coalition)to use military power to ostracize the Baath Party and its strong leader;Saddam Hussein from his position of authority.The crux to this decision was specifically geared towards suspicion that Saddam had a hand in9/11attack on the U.S mainland and generally as part of the desired"global war on terror"(G.W.T)pronounced by President Bush as a swift response to the terrorist attack.By all occurrences,it is one of(if not)the most costly wars(in monetary and human costs terms)in recent war history and the height of its severity and brutality is reflected in the thousands of casualties to the involving agents and the billions of dollars spent.The war also served as the guinea-pig for the experimentation of a new policy/grand strategy enshrined by the Bush administration called"the Bush Doctrine".　　In a broader perspective,this thesis explores whether there is sufficient amount of evidence that contains elements of veracity to substantiate the claims given by the United States for the invasion of Iraq and how legitimate the action was in line with the laws of war and that of the United Nations.In addition to that,I employ theories to analyze the causes of war.Moreover,this paper looks at distinctive issue areas as the Bush Doctrine,reasons for the invasion(overt and covert),just war and the invasion of Iraq,legitimacy claim,and the United Nations position on the war.The thesis takes a neutralist-reservationist view and however,my primary aim will be centered to display evidence that the claims made by Bushs administration were hegemonic realist claims that had no iota of veracity and thus the invasion was illegitirnate and the end result was a failed policy encapsulated by ferocious consequences.