For the organizations involved, chemical terrorism has several clear-cut advantages over conventional or nuclear terrorism. First of all, chemical substances are more accessible and available. They can be manufactured using simple chemical processes known to any university student. The components are usually simple products that can be obtained in the free market without restrictions. Chemical terrorism is inexpensive and does not require extensive facilities.
Chemical substances have the advantage of mobility.
In contrast to a nuclear bomb, which is usually large and cumbersome and requires special vehicles and security in transport, small amounts of chemicals suffice for a chemical attack. For example a jar containing several hundred grams of a chemical substance may cause mass mortality and, of course, can be moved about easily, with no need for special preparations or security. Over the years, modern technology has made great progress in the detection of conventional weapons and explosives. Many countries have put this technology to practical use at sensitive facilities and in congested population centers. The technology for the detection of chemical substances, in contrast, has not been disseminated as widely and has not been used for preventative security in the foiling of terrorist attacks.