The W67 was an American thermonuclear warhead which was developed in the mid-1960s but then cancelled prior to any production or service use in 1967. The W67 was intended to be a new warhead for both land and sea based ballistic missiles, specifically the UGM-73 Poseidon and Minuteman III (LGM-30G) missiles. The design was developed by Lawrence Radiation Laboratory (now Lawrence Livermore National Laboratory). After its cancellation, the W68 warhead was used for the Poseidon and the W78 for the Minuteman III.