The Ohio class of nuclear-powered submarines includes the United States Navy's 14 ballistic missile submarines (SSBNs) and its four cruise missile submarines (SSGNs). Each displacing 18,750 tons submerged, the Ohio-class boats are the largest submarines ever built for the U.S. Navy. They are also the third-largest submarines ever built, behind the Russian Navy's Soviet era 48,000-ton Typhoon class, the last of which was retired in 2023, and 24,000-ton Borei class. Capable of carrying 24 Trident II missiles apiece, the Ohio class are equipped with just as many missiles as, if not more than, either the Borei class (16) or the deactivated Typhoon class (20).
The Vanguard class is a class of nuclear-powered ballistic missile submarines (SSBNs) in service with the Royal Navy. The class was introduced in 1994 as part of the Trident nuclear programme, and comprises four vessels: Vanguard, Victorious, Vigilant and Vengeance, built between 1986 and 1999 at Barrow-in-Furness by Vickers Shipbuilding and Engineering, now owned by BAE Systems. All four boats are based at HM Naval Base Clyde , 40 km (25 mi) west of Glasgow, Scotland.
A ballistic missile submarine is a submarine capable of deploying submarine-launched ballistic missiles (SLBMs) with nuclear warheads. These submarines became a major weapon system in the Cold War because of their nuclear deterrence capability. They can fire missiles thousands of kilometers from their targets, and acoustic quieting makes them difficult to detect, thus making them a survivable deterrent in the event of a first strike and a key element of the mutual assured destruction policy of nuclear deterrence. The deployment of ballistic missile submarines is dominated by the United States and Russia. In fact, 70% of nuclear warheads in the USA are carried by SSBN submarines.
A nuclear submarine is a submarine powered by a nuclear reactor, but not necessarily nuclear-armed. Nuclear submarines have considerable performance advantages over "conventional" submarines. Nuclear propulsion, being completely independent of air, frees the submarine from the need to surface frequently, as is necessary for conventional submarines. The large amount of power generated by a nuclear reactor allows nuclear submarines to operate at high speed for long periods, and the long interval between refuelings grants a virtually unlimited range, making the only limits on voyage times being factors such as the need to restock food or other consumables.
India possesses nuclear weapons and previously developed chemical weapons. Although India has not released any official statements about the size of its nuclear arsenal, recent estimates suggest that India has 172 nuclear weapons and has produced enough weapons-grade plutonium for up to 200 nuclear weapons. In 1999, India was estimated to have 800 kilograms (1,800 lb) of separated reactor-grade plutonium, with a total amount of 8,300 kilograms (18,300 lb) of civilian plutonium, enough for approximately 1,000 nuclear weapons. India has conducted nuclear weapons tests in a pair of series namely Pokhran I and Pokhran II.
The Strategic Forces Command (SFC), sometimes called Strategic Nuclear Command, forms part of India's Nuclear Command Authority (NCA). It is responsible for the management and administration of the country's tactical and strategic nuclear weapons stockpile. It was created on 4 January 2003 by the Vajpayee Government. Air Marshal Teja Mohan Asthana became its first commander-in-chief.
The Borei class, alternate transliteration Borey, Russian designation Project 955 Borei and Project 955A Borei-A, are a series of nuclear-powered ballistic missile submarines being constructed by Sevmash for the Russian Navy. The class has been replacing the steadily retiring Russian Navy Delta III and Delta IV classes and fully retired Typhoon, all three classes being Soviet-era submarines.
A nuclear triad is a three-pronged military force structure of land-based intercontinental ballistic missiles (ICBMs), submarine-launched ballistic missiles (SLBMs), and strategic bombers with nuclear bombs and missiles. Countries build nuclear triads to eliminate an enemy's ability to destroy a nation's nuclear forces in a first-strike attack, which preserves their own ability to launch a second strike and therefore increases their nuclear deterrence.
Sagarika, also known by the code names K-15 or B-05 or PJ-08, is an Indian submarine-launched ballistic missile (SLBM) with a range of 750 kilometres (466 mi) that was designed for retaliatory nuclear strikes. It belongs to the K Missile family and forms a part of India's nuclear triad.
The Arihant-class is a class of Indian nuclear ballistic missile submarines under construction for the Indian Navy. They were developed under the ₹900 billion (US$11 billion) Advanced Technology Vessel (ATV) project to design and build nuclear-powered submarines. These vessels are classified as 'strategic strike nuclear submarines' by India.
INS Arihant, designated S2 Strategic Strike Nuclear Submarine, is the lead ship of India's Arihant class of nuclear-powered ballistic missile submarines. The 6,000 tonne vessel was built under the Advanced Technology Vessel (ATV) project at the Ship Building Centre in the port city of Visakhapatnam.
K-4 or Kalam-4 is a nuclear capable intermediate-range submarine-launched ballistic missile developed by the Defence Research and Development Organisation of India to arm its Arihant-class submarines. The missile has a maximum range of about 4000 km which offers greater operational flexibility compared to its predecessor K-15 having a limited shore-bounding range. On deployment, the missile will be the first to operationalise India's sea-based nuclear triad and can accommodate the demand of credible second-strike capability of its nuclear doctrine.
INS Varsha is a new naval base being developed under Project Varsha for the Indian Navy. This base will be the home of the navy's new fleet of nuclear submarines and ships. It was planned to be located within a radius of approximately 200 kilometres from Visakhapatnam, the headquarters of the navy's Eastern Naval Command. Previous news reports suggested that Gangavaram had been the initial site for the new base. The base is now being developed at Rambilli, which is 50 km from Visakhapatnam.
The K family of missiles, is a family of submarine-launched ballistic missiles (SLBM) developed by India to boost its second strike abilities and thus augment its nuclear deterrence. Information about this family of missiles has mostly been kept classified. It is reported that 'K missiles' are faster, lighter and stealthier than their Agni missile counterparts. High Energy Materials Research Laboratory (HEMRL) developed a new formulation of composite propellant that is more efficient and provide greater thrust compare to Agni missile series. The objective behind the development is to make K missile family faster and lighter without compromising on operational range.
INS Arighaat is an upgraded variant of the Arihant-class submarine. It is the second nuclear-powered ballistic missile submarine made by India under the Advanced Technology Vessel (ATV) project to build nuclear submarines at the Ship Building Centre in Visakhapatnam. It has the code name S3.
USHUS is an Integrated Submarine Sonar System developed by the Naval Physical and Oceanographic Laboratory (NPOL) of the Defence Research and Development Organisation (DRDO) of India and manufactured by Bharat Electronics Limited (BEL). It has been developed for use in submarines of the Indian Navy, especially for Sindhughosh-class submarines. Some reports also suggest that Arihant-class nuclear ballistic missile submarines are also equipped with USHUS system. USHUS replaces Russian systems like MGK-400 and MGK-519 sonars on Indian submarines.
Project 77 is a of the Indian Navy acquisition programme to procure nuclear-powered attack submarines. The Government of India, through the Cabinet Committee on Security (CCS), approved the construction of six of these submarines in February 2015. These will be designed by the Navy's in-house Directorate of Naval Design and built in India at the Ship Building Centre at Visakhapatnam. The construction was expected to commence on 2023-24 while the first submarine is expected to enter service in 2032. However, further and final clearance for initially acquiring 2 nuclear submarines, under the Project 77, was approved by CCS on 10 October 2024.
K-5 is a submarine-launched ballistic missile under development by Defence Research and Development Organisation of India. The missile has a planned range of 6,000 kilometres.
K-6 is an intercontinental submarine-launched ballistic missile under development by the Defence Research and Development Organisation of India. The missile has a planned range of around 10,000 to 12,000 kilometres.
Indian Navy 
