Russia's invasion of Ukraine has led numerous analysts to assess the possible deployment of nuclear weapons. This, in turn, has raised the profile of the submarine-launched ballistic missile (SLBM) equipped forces operated by the permanent members of the United Nations Security Council (UNSC), namely, China, France, the US, the UK, and Russia, which currently carry out the deterrence role. Sub-surface ballistic missile-equipped, nuclear-powered submarines (SSBNs) are invariably indigenously-built.
India recently joined the elite group of nations that operate SSBNs, and is therefore a likely future candidate for UNSC membership.
The years immediately following World War II saw the leading military powers develop land- and air-launched nuclear-armed missiles under the doctrine of Mutually Assured Destruction (MAD), which was intended to minimise the possibility of further worldwide conflict.
The US also had the Regulus missile, which was carried by submarines but had to be launched when the sub was surfaced.
Strategists soon realised, though, that missiles launched from below the surface from hard-to-detect nuclear-powered submarines with virtually unlimited endurance would be far more effective. In 1959, therefore, the US Navy commissioned the first SSBN, USS George Washington.
Common factors among SSBNs include a top speed of 25 to 30 knots, passive and active sonars, and a self-defence armament of torpedoes. Some are also fitted with anti-shipping cruise missiles. This article analyses the current capabilities and continuing development of these seldom-reported vessels, which are arguably the world's most important and powerful warships.
China's first SSBN, Xia, was commissioned in 1983. It is armed with the JL-1 7 SLBM, which has a range of 2,500 kilometres. This 8,000-tonne vessel has experienced many technical problems, resulting in poor availability, but it remains in service, having had a major refit.
The backbone of the Chinese SSBN force now, however, is the 11,000-tonne Jin-class, which is armed with the 7,200-kilometre range JL-2 missile. Six boats of the class are reportedly in service. Some US intelligence sources have been quoted as saying that the Jin-class generates considerable noise and is therefore easy to track.
In the pipeline is a new class of SSBN, the Type 096, which is to be armed with the JL-3 SLBM. According to recent reports, the first submarine of the class is under construction in Bohai.
India's rapidly expanding navy has been preparing to join the SSBN "club" for many years and commissioned its first such vessel in 2016. Constructed by Naval Dockyard at Viskahapatnam, INS Arihant displaces 6,600 tonnes and can be armed with either 12 K-15/Sagarika missiles, which have a range of 750 kilometres, or four K-4 missiles, which can strike targets at a distance of 3,500 kilometres. Both missiles can be fitted with thermonuclear warheads. On October 14 this year, Arihant test-fired a K-15 missile.
Sister boat INS Arighat recently completed sea trials, and the first of a planned two follow-on boats is under construction.
Analysts have little doubt that the prospective targets for the Indian Navy's SLBMs are in China and Pakistan.
France relies upon a deterrent force of four 15,500-tonne Triomphant-class SSBNs. These boats, which replaced the Redoubtable-class, are armed with 16 M45 SLBMs, each of which can be fitted with up to 10 Multiple Independently Targeted Re-entry Vehicles (MIRV) fitted with thermonuclear warheads.
In 2021, Paris confirmed that defence contractor the Naval Group has been tasked with developing a new generation of SSBNs to replace the existing force. Four new boats are planned and are to enter service from 2035 onwards.
The backbone of the Russian SSBN force is the Delta IV-class, seven of which were built from 1991. All these 16,500-tonne boats remain in commission. They are equipped with the SS-N-23 Skiff SLBM, which has a range of 8,200 kilometres.
Dmitriy Donskoy, the last of the huge Typhoon-class SSBNs, has reportedly been withdrawn from front-line service, but three of the 24,000-tonne Borei-class have been commissioned so far, and four more are in build at the Sevmash shipyard. These boats are each armed with 16 RSM56 Bulava SLBMs, each of which can be fitted with 10 MIRVs.
The UK Royal Navy currently relies upon four boats of the 1990s-vintage Vanguard class. Each is fitted with 16 tubes for 12,000 kilometre-range American Trident II SLBMs. Each of these missiles carries eight MIRVs. Only eight missiles are normally embarked nowadays, but this is currently under review.
The Vanguards are to be replaced by four new boats of the Dreadnought-class, which will also carry Trident missiles . At 19,000 tonnes, they will be slightly bigger than the vessels which they will replace. The first two examples are under construction by BAE Systems, with the initial unit scheduled to be in service by the early 2030s.
The US Navy is the biggest operator of SSBNs, with 14 Ohio-class boats on strength, having been commissioned from 1981 onwards. These 18,750-tonne vessels each carry 24 Trident II missiles with a range of 11,500 kilometres. Each missile can carry 12 MIRVs. The Ohio-class is to be progressively replaced by the Columbia-class boats from 2031.
The nuclear power plants of these vessels, which are set to displace more than 21,000 tonnes, are designed so as not to require refueling during the life of the boat, and will be inked to pump-jet propulsion. They will each be fitted with 16 firing tubes for the latest Trident missiles. Prime contractor is Electric Boat, and construction of the lead submarine in the class is underway.