Read the full, comprehensive report, Post-9/11 Islamic Extremism in the United States (PDF).
The ideologies of extreme intolerance that motivated the 19 hijackers responsible for carrying out the September 11, 2001, terrorist attacks continue to pose a serious threat to the U.S.
While no attacks of that magnitude have been successful on American soil in the ten years since 9/11, one of the most striking elements of today's terror threat picture is the role that a growing number of American citizens and residents motivated by radical interpretations of Islam have played in criminal plots to attack Americans in the United States and abroad.
Although they do not constitute a fully coherent movement in the U.S., more and more American citizens and residents are being influenced by ideologies that justify and sanction violence commonly propagated by Islamic terrorist movements overseas.
In addition to disagreements with perceived American actions against Muslims around the world, these extremists believe that the West (and America specifically) is at war with Islam and it is the duty of Muslims to defend the global Muslim community through violent means. They come from diverse backgrounds and, as a whole, do not easily fit a specific profile. About one fourth are converts to Islam who embrace the most extreme interpretations of the religion.
The most common targets in the U.S. have been military installations, major landmarks, transit systems and Jewish or Israeli institutions. In fact, hatred of Jews and Israel has played an alarming role in the radicalization process of many of these same homegrown extremists.
Although most individuals or groups lack the means and materials to carry out violent attacks – plots have been foiled by law enforcement at various stages – they continue to demonstrate a willingness to conduct attacks in the U.S.