Counterterrorism can be divided into four functions. Prevention consists of the avoidance of terrorist incidents by denying access to suitable instruments, by successful protection of critical targets, or by deterring incidents through a combination of denial and protection. Control involves the timely establishment of mechanisms for the command and control of government resources to assure an efficient response to an incident. Containment is composed of emergency measures to delimit the physical and psychological impact of a terrorist act. Restoration involves actions to conclude the event and restore the situation to normal. The use of technology in prevention involves establishing a variety of routine procedures and barriers that would inhibit all but the most sophisticated terrorists in their access to likely targets. This would include the use of devices that could detect a wide variety of poisons, explosives, and drugs. The general use of such devices with all similar likely targets is essential for effective prevetion. Some methods for detecting explosives are the use of specially trained dogs and electron-capture vapor detectors. The impregnation of detonators with distinctive chemicals at manufacture would aid detection. The development of increasingly sophisticated metal detectors and X-ray machines can also help in detecting various weapons that might be carried in luggage and cargo. The control and containment phases of terrorist problems contrast sharply with the prevention and restoration phases. Because the focus is on actual threats, rapid access to highly specialized equipment and experts tailored to the particular event is required. This phse requires development of highly specialized devices for more limited use rather than general-use devices appropriate for the prevention and restoration phases. The technology used in restoration would approach that used in any health and safety crisis.