http://www.fbi.gov/hq/nsb/wmd/wmd_home.htm
WHY THERE IS A NEED FOR FBI / CBI AMALGAMATION !
What is a Weapon of Mass Destruction?

Any explosive or incendiary device, as defined in Title 18 USC, Section 921: bomb, grenade, rocket, missile, mine, or other device with a charge of more than four ounces;
Any weapon designed or intended to cause death or serious bodily injury through the release, dissemination, or impact of toxic or poisonous chemicals or their precursors;
Any weapon involving a disease organism; or
Any weapon designed to release radiation or radioactivity at a level dangerous to human life.