The W80 is a small thermonuclear warhead (fusion or, more descriptively, two-stage weapon) in the enduring stockpile with a variable yield of between 5 and 150 kt of TNT. It was designed for deployment on cruise missiles and is the warhead used in the majority of nuclear-armed US Air Force ALCM and ACM missiles, and their US Navy counterpart, the BGM-109 Tomahawk. It is essentially a modification of the widely deployed B61 weapon, which forms the basis of most of the current US stockpile. The very similar W84 warhead was deployed on the BGM-109G Gryphon GLCM.