E133 cluster bombThe E133 cluster bomb was a U.S. biological weapon developed during the Cold War.HistoryThe U.S. E133 cluster bomb was developed prior to Richard M. Nixon's 1969 declaration that ended the U.S. [biological weapons program]. 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.SpecificationsThe E133 cluster weighed 750 pounds. It held between 536 and 544 E61 bomblets, which when dropped would detonate on impact dispersing an aerosol of biological agent, usually anthrax.