The U.S. is fighting a "war on terror," while Europe's battles against terrorists largely take place in the courtroom. Here is a look at the tensions in the trans-Atlantic relationship that have developed out of this pursuit of differing strategies.

An examination of the ideology that has inspired the global jihad and the emergence of its most dangerous incarnation.

Europe's 18 million Muslims represent the continent's fastest growing religion; however this community of immigrants who share religious and ethnic bonds has largely failed to integrate into European societies founded on secular principles. Here is an examination of this clash of cultures.

For all the fear that cyber terrorists will turn the Internet into a weapon of mass disruption, many intelligence experts contend the Web is most effective (or detrimental) as it was designed to be -- as a way to communicate and create community. This essay explores how jihadis are using the Web, plus some of the cyber "tricks" used by terrorists to avoid detection and how the authorities can respond.

Each year, under the terms of the Visa Waiver Program, more than 10 million citizens from 27 countries -- mostly in Europe -- enter the U.S. for 90 days or less without being required to go through the screening process of first obtaining a visa. Although it offers great economic benefits for the U.S., critics argue that terrorists who carry passports from these countries can easily gain entry to the U.S. and that the security risks outweigh the benefits of the program. Here are the pros and cons.

A look at the challenges facing European and American officials as they struggle to crack down on terrorist financing.

Nizar Trabelsi is a former professional soccer player turned Islamic militant who planned to blow up a NATO airbase in Belgium. Here is a close examination of his case, which provides a glimpse at the challenges facing counterterrorism officials. Plus, a chronology of other significant plots uncovered in Europe both before and after 9/11.