The Mark 27 nuclear bomb and closely related W27 warhead were two American thermonuclear weapon designs from the late 1950s.
The basic design concept competed with the Los Alamos Scientific Laboratory (LASL; now Los Alamos National Laboratory) design that would become the Mark 28 / B-28 nuclear bomb and W28 warhead.
[2] The Mark 27 and W27 were produced from 1958; both were retired by 1964, as the Kennedy administration began to redirect funding from manned nuclear bomber programs.
Both US Navy bombers carrying the Mark 27 bomb, the Douglas A-3 Skywarrior and North American A-5 Vigilante, were repurposed from the nuclear strike role to tanker, electronic countermeasure (A-3) or reconnaissance (A-5) roles by 1965.
20 W27 warheads were produced for the United States Navy SSM-N-9 Regulus II cruise missiles.