	Background

Current popular attention being paid to the threat of chemical and biological weapons (CBW)use by terrorists may give the impression that this is a new phenomenon, but it is not. Possible Reasons for Increased Terrorist Use

The reasons for increased potential use can be grouped into four major categories: the growthof militant religious groups with political agendas as a percentage of all terrorist groups, theincreasing global availability of CBW information and stockpiles, the internationalization of thethreat of terrorism, and the clear evidence of terrorist interest and capabilities. First, there has been a sharp increase in militant religious groups internationally as a percentage of all terrorist groups. If measured strictly in terms of their proven capacity to kill people or thefrequency of terrorist use in the past, CBW weapons are not the most worrisome threat. It is difficult in most scenarios to execute an attack with chem-bioweapons that kills a large number of people. Within the United States, some measures enhancing the security oflaboratories/facilities have already been enacted.
There is widespread belief that the likelihood of terrorist use of chemical and biological weapons (CBW) is increasing, in part as a result of publicized new evidence of terrorist interest andcapabilities, as well as the political fall-out from the war in Iraq. This is a serious present concernthat deserves examination in the broader framework provided by the patterns, motivations andhistorical context for the current terrorist threat. Although it can have a powerful psychologicalimpact, past CBW use by terrorists has been rare and has not caused a large number of casualties,especially compared to other weapons. Terrorist attacks are deliberately designed to surprise, so notrend analysis will ever perfectly predict them, especially in the contemporary international climate. This report presents the arguments for and against future nonstate terrorist acquisition and/or use ofCBW weapons against the United States, as well as a brief discussion of issues for congressconcerning how best to counter the threat. It will not be updated.