"Although the vast majority of Muslims in Europe are not involved in radical activities, Islamist extremists and vocal fringe communities that advocate terrorism exist and reportedly have provided cover for terrorist cells. Germany and Spain were identified as key logistical and planning bases for the September 11, 2001 attacks on the United States. The March 2004 terrorist bombings in Madrid have been attributed to an Al Qaeda-inspired group of North Africans. UK authorities have named four British Muslims as the perpetrators of the July 2005 terrorist attacks on London; in August 2006, British law enforcement arrested several British Muslims suspected of plotting to blow up airliners flying from the UK to the United States. This report provides an overview of Islamist extremism in Europe, possible terrorist links, European responses, and implications for the United States."
CRS Report for Congress, RS22211