The United States is a nation at war. It will be a long war. The terrorist attacks on 11 September 2001 were the catalyst that brought the US to this war: the Global War on Terrorism. However, US and coalition responses to Islamic extremism since 11 September 2001 have not prevailed and in some cases have exacerbated the problem of Islamic radicalization even further. It is increasingly clear that understanding the root causes or sources of Islamic extremism is critically important to designing a viable long-term strategy to counter or eliminate them. In general terms, this thesis seeks to identify the sources of Islamic extremism. Specifically, this thesis seeks to answer the question, Has The National Security Strategy of the United States of America March 2006 properly identified the sources of Islamic extremism? In doing so, this thesis considers multiple perspectives including those of the US government, international organizations, nongovernmental organizations and experts, and Islamic extremists themselves.