Submarine-launched ballistic missile (
SLBM) is a
ballistic missile capable of delivering a
nuclear warhead that can be launched from
submarines. Modern variants usually deliver
multiple independently targetable reentry vehicles (MIRVs) each of which carries a
warhead and allows a single launched missile to strike several targets.
History
As early as 1934,
H. G. Wells predicted, in his
The Shape of Things to Come, the use of submarines carrying "long-range air torpedoes with directional apparatus". Though he envisaged these as carrying chemical rather than nuclear warheads, he grasped the far reaching strategic implications. "The smallest of these raiders carried enough of such stuff to 'prepare' about eight hundred square miles of territory; it could have turned London or New York into a cityful of distorted corpses. These vessels made London vulnerable to Japan, Tokyo vulnerable to Dublin; they abolished the last corners of safety in the world."
The first successful tests of a submarine-based launch platform were by German
submarines in
World War II using a submarine towed launch platform. These and other early SLBM systems required vessels to be surfaced when they fired missiles, but after World War II, launch systems were quickly adapted to allow underwater launching, with the United States making the first underwater launch of a
Polaris.
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 very close range attack which will hit its target in a matter of minutes, thus opening the possibility of a
decapitation strike.
Types of SLBMs

Montage of the launch of a
Trident C4 SLBM and the paths of its reentry vehicles.
Specific types of SLBMs (current, past and under development) include:- *RSM-45 R-31 also known as SS-N-17 "Snipe"
- *R-16 also known as SS-N-17 "Snipe" [reference to R-16 is erroneous)
- *M51 SLBM, under development and expected to enter service by 2010
- *JL-2, under development and expected to enter service by 2010
- *K-15, under development and expected to enter service by 2010
- *K-X , underdevelopment SLBM version of Agni-III.
Types of SSBNs
Specific types of
ballistic missile submarines (SSBNs) include:
See also