The World Trade Center bombers are a new breed of terrorist. Unlike the tightly disciplined cells that dominated terrorism in the past, they functioned in a loosely organized ad hoc manner. The bombers were all either recent immigrants or illegal aliens. Rejecting assimilation into the resented society of their host country, they were susceptible to incitement by Sheik Omar Abdul Rahman, the spiritual leader of a radical fundamentalist movement that has waged a terrorist campaign to overthrow the Egyptian government. The new breed of radical Islamic terrorist is more intractable, less likely to betray other terrorists, and more unpredictable than previous terrorist groups. Instead of using terrorism to influence Western powers to change their policies, as was the case with Palestinian terrorist groups in the past, the Islamic groups often use terrorism to punish Western powers and inspire other Muslims to rise up against the West. Ironically, many radical Islamic movements outlawed in their own countries have found sanctuary in Western countries. They operate under the protection of laws based in democratic principles, although they oppose the values of the societies where they reside. U.S. counterterrorism officials worry that "sleeper cells" already established within the United States could be dormant for many years until activated for specific terrorist actions.