Tactical Oxygen Nuke, or simply "Nuke", refers to grenade-sized tactical nuclear munitions used by the Mobile Infantry in the First Bug War. Unlike fission or fission-fusion nuclear weapons, the nuclear weapon used in the film appears to be an ultra-low yield pure fusion weapon. Pure fusion releases energy like conventional nuclear weapons but doesn't require fissile materials such as Plutonium or Uranium and therefore produce no fallout. This allows the Mobile Infantry to destroy huge Plasma bugs and then immediately rush into the area in the early stage of the Klendathu Offensive.