the maintenance of a block of pine. In January 1961, Sandia was requested to develop an environmental safing device for the weapon. This was achieved with an inertial switch, producing the Mark 25 Mod 1 warhead. The weapon entered the stockpile in March 1962. The W25 was retired in 1984. Atomic demolition munition In October 1953, it was recommended that a lightweight atomic demolition munition (ADM) be developed. The device would be in diameter, in length, weigh less than and be capable of disassembly into packages. The application was cancelled in favor of ADMs based on the Mark 30 and Mark 31 in February 1956. Little John In September 1954, the US army began examining warheads for the MGR-3 Little John rocket (originally called Honest John Junior). Military characteristics for a warhead were provided in April 1955 and the W25 warhead was briefly considered for the role. In February 1956, the application was cancelled in favor of a higher-yield, smaller diameter weapon. The W45 warhead was eventually selected for the missile. Boosted and all-uranium warhead In June 1956, informal comments were made about the lack of a boosted W25 warhead. Albuquerque Operations Office replied that no formal request for such a weapon had ever been received and the military promptly furnished such a request. In July 1956, a preliminary study was concluded stating that, because of the size limitations of the Genie application, a complete redesign would be needed, effectively producing a new warhead. That study was followed by concerns about the plutonium hazard of the W25 and queries about producing an all-uranium weapon. A study group was convened which reported in November 1956 that, while the plutonium hazard could be reduced to some degree, inside the space limitations given, an all-uranium warhead was not possible without utilizing a gun-type device. In May 1957, the AEC was directed to examine ways to minimize the plutonium hazard without increasing fissile material requirements. The results of that study remain classified, but the application was cancelled in November 1957. Design The W25 was in diameter and long, with a reported weight of . The warhead was an implosion weapon and was of the sealed design. See also List of nuclear weapons References Nuclear warheads of the United States Tactical nuclear weapons Military equipment introduced in the 1950s