The book analyzes the United States' foreign security policy and its changes since the end of WW II until the present day. The first part describes foreign security concepts of the USA during the Cold War and in the "chaotic" 90s. The second chapter represents the core of the book; it analyzes the metamorphosis of the US foreign policy after the attacks of 9/11 with emphasis on the Bush doctrine embodied in the National Security Strategy of the United States of America (2002) and its subsequent impacts on the international community. Finally, the last chapter is devoted to President Obama's foreign security strategies, looking at whether it represents a real shift from his predecessor or just a change of rhetoric.