The E133 cluster bomb was a U.S. biological weapon developed during the Cold War.
The U.S. E133 cluster bomb was developed prior to Richard M. Nixon's 1969 declaration that ended the U.S. biological weapons program.[1] At the time of Nixon's declaration the E133 was considered the most likely candidate in the U.S. biological arsenal to actually be used in a combat situation.[1]
The E133 cluster weighed 750 pounds.[2] It held between 536[3][1] and 544[2] E61 bomblets, which when dropped would detonate on impact dispersing an aerosol of biological agent,[3] usually anthrax.