SLBM

A submarine-launched ballistic missile (SLBM) is a ballistic missile capable of being launched from submarines. Modern variants usually deliver multiple independently targetable reentry vehicles (MIRVs) each of which carries a nuclear warhead and allows a single launched missile to strike several targets. Submarine-launched ballistic missiles operate in a different way from submarine-launched cruise missiles.

Modern submarine-launched ballistic missiles are closely related to intercontinental ballistic missiles (range of over 5,500 kilometres (3,000 nmi)), and in many cases SLBMs and ICBMs may be part of the same family of weapons.

The first practical design of a submarine-based launch platform was developed by the Germans near the end of World War II involving a launch tube which contained a V-2 ballistic missile variant and was towed behind a submarine, known by the code-name Prüfstand XII. The war ended before it could be tested, but the engineers who had worked on it went on to work for the USA and USSR on their SLBM programs. These and other early SLBM systems required vessels to be surfaced when they fired missiles, but launch systems eventually were adapted to allow underwater launching in the 1950-1960s. A converted Project 611 (Zulu-IV class) submarine launched the world's first SLBM, an R-11FM (SS-N-1 Scud-A, naval variant of the SS-1 Scud) on 16 September 1955. Five additional Project V611 and AV611 (Zulu-V class) submarines became the world's first operational ballistic missile submarines (SSBNs) with two R-11FM missiles each, entering service in 1956–57.

The United States Navy initially worked on a sea-based variant of the US Army Jupiter intermediate-range ballistic missile, projecting four of the large, liquid-fueled missiles per submarine. Rear Admiral W. F. "Red" Raborn headed a Special Project Office to develop Jupiter for the Navy, beginning in late 1955. However, at the Project Nobska submarine warfare conference in 1956, physicist Edward Teller stated that a physically small one-megaton warhead could be produced for the relatively small, solid-fueled Polaris missile, and this prompted the Navy to leave the Jupiter program in December of that year. Soon Chief of Naval Operations Admiral Arleigh Burke concentrated all Navy strategic research on Polaris, still under Admiral Raborn's Special Project Office. All US SLBMs have been solid-fueled while all Soviet and Russian SLBMs have been liquid-fueled except for the Russian RSM-56 Bulava, which entered service in 2014.

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