streets, buses, trains, and subways are vulnerable.Other aspects favor an attack: Public transportationcenters offer easy access and escape, if escape is aplanning factor. Contained environments, like asubway, increase the effects of explosives and thelikelihood of panic and mayhem after an attack.Transportation systems normally concentratepeople; these concentrations increase the probabili-ty of mass casualties and effects. The greatest con-cerns in preventing a catastrophic terrorist incidentare (1) the threat of covert operatives, whether asleeper-type cell or a recently recruited operative,inside the U.S. with an intention to assist or conducta terrorist attack; (2) the clear intention of al Qaedato obtain and use a WMD against the United States;and (3) the potential for al Qaeda to leverage otherextremist persons or groups to assist or conductattacks on the United States.U.S. domestic terrorists and other internationalterrorist groups pose a threat too. Political and so-cial agendas include white supremacy, black sepa-ratism, animal rights, environmental protection, an-archism, anti-abortion, right-wing Patriot movementthemes, and ethnic Homeland or religious ideologythemes. In a recent instance, the FBI uncovered analleged terrorism plot by Americans to target syna-gogues and military recruiting centers around theLos Angeles area (see the Case Study—JIS in thischapter). The London bombings indicate that a personcan take an extreme concept and recruit targetedindividuals into a small group of committed terror-ists. He can gather and provide the means for mak-ing and delivering devastating weapon effects andattack while attempting to mask mass murder witha radical ideology and justification.The danger to the Homeland remains real. Thelargest mass transit systems in the United States sup-port New York City, Chicago, Los Angeles, Boston,and Washington, DC. When Khalid Sheik Muham-med, a chief subordinate to Osama bin laden, wascaptured, he stated during his interrogation that alQaeda planned to attack the Washington, DC metro(subway) system. Risk assessment and managementis a colossal task for any of the transportation sys-tems. For example, New York City has more thanseven million daily commuters using its network ofbuses, trains, and subways. Consider just the tunnelnetwork of the New York City Metropolitan Trans-portation Authority. The transportation network in -cludes 14 tunnels that link four of the city’s five bor-oughs under three bodies of water—the East River,the Harlem River, and Newtown Creek (Prieto,2005). In 1997, law enforcement uncovered andprevented an Islamic terrorist bomb attack on theNew York City subway system. Another terrorist at-tempt to bomb the New York City subway systemwas prevented in 2004 before the Republican Na-tional Convention (Hedges, 2006).