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 factors such as the need to restock food or other consumables.

[2] Thus nuclear propulsion solves the problem of limited mission duration that all electric (battery or fuel cell powered) submarines face.

[3][4] The idea for a nuclear-powered submarine was first proposed in the United States Navy by the Naval Research Laboratory's physicist Ross Gunn in 1939.

[6] Construction of the world's first nuclear-powered submarine was made possible by the successful development of a nuclear propulsion plant by a group of scientists and engineers in the United States at the Naval Reactors Branch of the Bureau of Ships and the Atomic Energy Commission.

After overcoming many obstacles, including steam generation problems, radiation leaks, and other difficulties, the first nuclear submarine based on these combined efforts, K-3 Leninskiy Komsomol of the Project 627 Kit class, called a November-class submarine by NATO, entered service in the Soviet Navy in 1958.

[9] The United Kingdom's first nuclear-powered submarine HMS Dreadnought was fitted with an American S5W reactor, provided to Britain under the 1958 US-UK Mutual Defence Agreement.

[6] During Dreadnought's construction, Rolls-Royce, in collaboration with the United Kingdom Atomic Energy Authority at the Admiralty Research Station, HMS Vulcan, at Dounreay, developed a completely new British nuclear propulsion system.

[13] Nuclear power proved ideal for the propulsion of strategic ballistic missile submarines (SSB), greatly improving their ability to remain submerged and undetected.

The first Soviet SSBN with 16 missiles was the Project 667A (Yankee class), the first of which entered service in 1967, by which time the US had commissioned 41 SSBNs, nicknamed the "41 for Freedom".

From the late 1950s through the end of 1997, the Soviet Union, and later Russia, built a total of 245 nuclear submarines, more than all other nations combined.

[23][24] The decommissioning of these submarines is a long process; some are held in reserve or mothballed for some time and eventually scrapped, others are disposed of immediately.

[23][24] After sealing the submarine it can then be towed to a designated deep-sea disposal site, be flooded and settle intact on the sea floor.

It is expected to be launched from specially-designed Belgorod class submarines, and to hit large coastal cities as a second strike weapon.

The main advantage of using unmanned underwater vehicles instead of SSBNs as a second strike weapon is to prevent the loss of lives of the SSBN crew.

When an UUV delivers a nuclear charge, the location of the mothership remains unknown, and the ship is likely to survive the 3rd strike.