This thesis is an analysis of the foreign policy of the Bush administration and the degree to which it is a part of the greater tradition of common American foreign policy. From a theoretical perspective, the work is essentially realist, although the inclusion of some conventional constructivism is aimed at adding to the analysis. These different theoretical approaches are reconciled by the positioning of the role of ideas as an intervening variable in a neoclassical realist logic, which treats the distribution of power in the international system as the independent variable and the foreign policy outcomes as the dependent variable. In empirical terms, the work identifies the collapse of the USSR and the absence of a replacement major power as the key determinant of American foreign policy during this period, and the events of 9/11 as the specific and immediate catalyst for the development and implementation of the Bush doctrine. But in conjunction with these material factors, and crucial to the direction of American foreign policy during this period, is the salience of neoconservatism in the administration, which this work classifies as a form of 'realist idealism'. With this in mind, the structure is divided into sections on International Relations theory; American grand strategy; the origins of 9/11 and the Bush doctrine; issues of missile defence and nuclear strategy; the interventions in Afghanistan and Iraq; the containment of Iran and North Korea; and an examination of major power relations in the post 9/11 era. The generic premise of this work is that the US always has and always will base its foreign policy on calculations of its own vital national interest. In terms of the future of American diplomacy, this work predicts there will be a shift from the 'War on Terror' back to a greater emphasis on major power relations and a rise in the salience of China, Russia and India in world politics. It also notes that the US will develop its relationship with countries in South East Asia and also Australia due to the economic and material resources in these locations and also their geopolitical significance