A blue-ribbon Congressional panel led by former Florida Senator Bob Graham determined that the United States is likely to suffer an attack by weapons of mass destruction before 2013, and that the attack is more likely to be a biological attack than a nuclear one. The panel cited the accessibility and poor security exercised over the storage of biological pathogens as factors in their risk determination.CNN: Biological Terror Attack Likely by 2013, Panel Says (December 2, 2008)

During the Second World War, the Japanese government maintained a bioweapons program in Manchuria that produced bacteriological bombs containing plague and anthrax. The Japanese dropped these bombs on Chinese villages during the Second World War. To test the biological agents, the Japanese forced Chinese prisoners to eat and inhale the pathogens; in some cases, the Japanese would kill the subjects before they had died in order to perform autopsies.American Experience: Timeline: Biological Weapons

"The consequences of a biological attack are almost beyond comprehension. It would be 9/11 times 10 or a hundred in terms of the number of people who would be killed... Today [the 1918 flu virus] is still in the laboratory, but if it should get out and into the hands of scientists who knew how to use it for a violent purpose, we could have multiple times the 40 million people who were killed 100 years ago."—Former Senator Bob GrahamCNN: Biological Terror Attack Likely by 2013, Panel Says (December 2, 2008)