CBU-55

The CBU-55 was a cluster bomb fuel–air explosive that was developed during the Vietnam War by the United States Air Force, and was used only infrequently in that conflict. Unlike most incendiaries, which contained napalm or phosphorus, the 750-pound (340 kg) CBU-55 was fueled primarily by propane. Described as "the most powerful non-nuclear weapon in the U.S. arsenal" until then, the device was one of the most powerful conventional weapons designed for warfare.