Explosive devices are the most common terrorist weapons because their materials and technology are more readily available than those of biological, chemical, nuclear, or radiological weapons. Of course, explosions also may be involved with or used to disperse these and other threat agents.
Terrorists can use either manufactured or improvised explosive devices in public places and against a wide variety of vessels, building, and institutions. Such devices can be hidden, delivered by humans, transported in vehicles, and even mailed or shipped. They may be detonated directly or remotely by timing, tampering, or impact.