Submarine-launched ballistic missile
A submarine-launched ballistic missile (SLBM) is a ballistic missile capable of being launched from some 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, 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 ballistic missile and was towed behind a submarine. 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. The United States made the first successful underwater launch of a Polaris A1 on 20 July 1960. Forty days later, the Soviet Union made its first successful underwater launch of a submarine ballistic missile in the White Sea on 10 September 1960 from the same converted Project 611 (Zulu Class) submarine that first launched the R-11FM (SS-N-1 Scud-A, naval modification of SS-1 Scud) on 16 September 1955. However, the Soviet Union was able to beat the U.S. in launching and testing the first armed SLBM, an R-13 that detonated in the Novaya Zemlya Test Range in the Arctic Ocean, doing so on October 20, 1961, just ten days before the gigantic 50 MT Tsar Bomba's detonation in the same general area.
Ballistic missile submarines have been of great strategic importance for the USA and Russia and other nuclear powers since the start of the Cold War, as they can hide from reconnaissance satellites and fire their nuclear weapons with virtual impunity. This makes them immune to a first strike directed against nuclear forces, allowing each side to maintain the capability to launch a devastating retaliatory strike, even if all land-based missiles have been destroyed. This relieves each side of the necessity to adopt a launch on warning posture, with its grave attendant risk of accidental nuclear war. Additionally, the deployment of highly accurate missiles on ultra-quiet submarines allows an attacker to sneak up close to the enemy coast and launch a missile on a depressed trajectory (a non-optimal ballistic trajectory which trades off reduced throw-weight for a faster and lower path, effectively reducing the time between launch and impact), thus opening the possibility of a decapitation strike.
Types of SLBMs
Specific types of SLBMs (current, past and under development) include:
- United States of America (also known as Fleet Ballistic Missiles)
- UGM-27 Polaris – Decommissioned
- UGM-73 Poseidon – Decommissioned
- UGM-96 Trident I (C4) – Decommissioned
- UGM-133 Trident II (D5) - Operational
- R-13 NATO name SS-N-4 – Decommissioned
- R-21 NATO name SS-N-5 – Decommissioned
- RSM-25  R-27 NATO name SS-N-6 – Decommissioned
- RSM-40  R-29 "Vysota", NATO name SS-N-8 "Sawfly" – Decommissioned
- R-27K, NATO name SS-NX-13 - designed for anti-ship use, never operational 
- RSM-45 R-31 NATO name SS-N-17 "Snipe"  – Decommissioned
- RSM-50  R-29R "Vysota", NATO name SS-N-18 "Stingray" - Operational
- RSM-52  R-39 "Rif", NATO name SS-N-20 "Sturgeon" – Decommissioned
- RSM-54 R-29RM "Shtil", NATO name SS-N-23 "Skiff" – Decommissioned (last ship is now under rebuild to R-29RMU "Sineva") 
- RSM-54 R-29RMU "Sineva", NATO name SS-N-23 "Skiff" - Operational
- RSM-54 R-29RMU2 "Layner" - Operational
- RSM-56 R-30 "Bulava", SS-NX-32 - Operational
- M1 – Decommissioned
- M2 – Decommissioned
- M20 – Decommissioned
- M4 – Decommissioned
- M45 – Operational
- M51 - Operational
- K-15 Sagarika - Under development （only test fired from submerged pontoons）
- K-4 - Under development
- K-5 – Under development
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- "JL-1 [CSS-N-3] - China Nuclear Forces". Fas.org. Retrieved 2012-02-10.
- 'INS Arihant' to sail on deterrent patrol after commissioning[dead link]
|Wikimedia Commons has media related to: Submarine-launched ballistic missiles|
- Video showing the launch of a Trident SLBM.
- Estimated Strategic Nuclear Weapons Inventories (September 2004)
- R-11 SLBM
- Trident Submarines Are Killing Machines Unparalleled In Human History.[dead link]