An SSN is a
nuclear-powered
Nuclear power is the use of nuclear reactions to produce electricity. Nuclear power can be obtained from nuclear fission, nuclear decay and nuclear fusion reactions. Presently, the vast majority of electricity from nuclear power is produced b ...
general-purpose
attack submarine
An attack submarine or hunter-killer submarine is a submarine specifically designed for the purpose of attacking and sinking other submarines, surface combatants, and merchant vessels. In the Soviet Navy, Soviet and Russian Navy, Russian navies ...
. ''SSN'' is the
US Navy hull classification symbol
US or Us most often refers to:
* ''Us'' (pronoun), the objective case of the English first-person plural pronoun ''we''
* US, an abbreviation for the United States
US, U.S., Us, us, or u.s. may also refer to:
Arts and entertainment Albums
* ...
for such vessels; the ''SS'' (as 'Ship Submersible') denotes a
submarine
A submarine (often shortened to sub) is a watercraft capable of independent operation underwater. (It differs from a submersible, which has more limited underwater capability.) The term "submarine" is also sometimes used historically or infor ...
and the ''N'' denotes
nuclear power
Nuclear power is the use of nuclear reactions to produce electricity. Nuclear power can be obtained from nuclear fission, nuclear decay and nuclear fusion reactions. Presently, the vast majority of electricity from nuclear power is produced by ...
. The designation SSN is used for interoperability throughout
NATO
The North Atlantic Treaty Organization (NATO ; , OTAN), also called the North Atlantic Alliance, is an intergovernmental organization, intergovernmental Transnationalism, transnational military alliance of 32 Member states of NATO, member s ...
under
STANAG
In NATO, a standardization agreement (STANAG, redundantly: STANAG agreement) defines processes, procedures, terms, and conditions for common military or technical procedures or equipment between the member countries of the alliance. Each NATO st ...
1166, though navies use other terms.
History
The first nuclear-powered attack submarine was the US Navy's , operational from 1954. This was followed by the four submarines of the entering service in 1957.
The Royal Navy's first nuclear fleet submarine was which by using an American reactor entered service in 1963. The first all-British nuclear submarines were the two s.
The USN submarine fleet has been all-nuclear powered for over three decades. The last Barbel-class diesel-electric attack submarine, , was decommissioned in 1990. The bulk of the USN's SSN fleet has been the
''Los Angeles''-class attack submarine. Designed during the
Cold War
The Cold War was a period of global Geopolitics, geopolitical rivalry between the United States (US) and the Soviet Union (USSR) and their respective allies, the capitalist Western Bloc and communist Eastern Bloc, which lasted from 1947 unt ...
the ''Los Angeles''-class boats ''raison d'etre'' was to protect USN
carrier battle groups and to hunt
Soviet Navy
The Soviet Navy was the naval warfare Military, uniform service branch of the Soviet Armed Forces. Often referred to as the Red Fleet, the Soviet Navy made up a large part of the Soviet Union's strategic planning in the event of a conflict with t ...
SSBNs before they could launch a first strike against the United States.
The first ever major combat action involving an SSN was during the 1982
Falklands War
The Falklands War () was a ten-week undeclared war between Argentina and the United Kingdom in 1982 over two British Overseas Territories, British dependent territories in the South Atlantic: the Falkland Islands and Falkland Islands Dependenci ...
. An Argentinian cruiser, was sunk by
torpedo
A modern torpedo is an underwater ranged weapon launched above or below the water surface, self-propelled towards a target, with an explosive warhead designed to detonate either on contact with or in proximity to the target. Historically, such ...
es fired by the Royal Navy fleet submarine . After that incident, the Argentinian Navy was effectively confined to port.
Since the end of the Cold War, SSNs have evolved into multi-mission submarines. Their roles include submarine-launched
cruise missile
A cruise missile is an unmanned self-propelled guided missile that sustains flight through aerodynamic lift for most of its flight path. Cruise missiles are designed to deliver a large payload over long distances with high precision. Modern cru ...
platforms, intelligence gathering platforms, insertion and exfiltration of
special forces
Special forces or special operations forces (SOF) are military units trained to conduct special operations. NATO has defined special operations as "military activities conducted by specially designated, organized, selected, trained and equip ...
teams in addition to traditional hunter-killer SSN roles.
The advantages of an SSN over a conventionally powered
SSK are much longer endurance (limited more by the crew than the boat, a nuclear submarine can stay submerged for months and does not need refueling in their 25-year lifespans), and higher speed. Unlike most SSKs, SSNs do not have to surface periodically for air, which would compromise their stealth. Some of the newest conventional submarines approach these advantages:
Stirling engine
A Stirling engine is a heat engine that is operated by the cyclic expansion and contraction of air or other gas (the ''working fluid'') by exposing it to different temperatures, resulting in a net conversion of heat energy to mechanical Work (ph ...
powered vessels can cruise underwater for up to two weeks and, like diesel/electric vessels (and in theory
LOX powered vessels), are significantly quieter than nuclear submarines, since they do not need to run the powerful (and noisy) pumps associated with the cooling circuits of pressurized water reactors.
The main disadvantages of an SSN are the technological challenges and expenses of building and maintaining a
nuclear power
Nuclear power is the use of nuclear reactions to produce electricity. Nuclear power can be obtained from nuclear fission, nuclear decay and nuclear fusion reactions. Presently, the vast majority of electricity from nuclear power is produced by ...
plant. Nuclear submarines can have political downsides, as some countries refuse to accept nuclear-powered vessels as a matter of policy. Furthermore,
decommissioned nuclear submarines require costly dismantling and long term storage of the
radioactive waste
Radioactive waste is a type of hazardous waste that contains radioactive material. It is a result of many activities, including nuclear medicine, nuclear research, nuclear power generation, nuclear decommissioning, rare-earth mining, and nuclear ...
.
Active SSN classes
;
United States Navy
The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 millio ...
(50 in service)
* – 23 in service, 39 retired
* – 3 in service
* – 24 in service, 16 ordered
*
SSN(X)-class submarine – under development
;
Russian Navy
The Russian Navy is the Navy, naval arm of the Russian Armed Forces. It has existed in various forms since 1696. Its present iteration was formed in January 1992 when it succeeded the Navy of the Commonwealth of Independent States (which had i ...
(21 in service)
*
Victor-class submarine
The Victor class, Soviet designations Project 671 ''Yorsh'', Project 671RT ''Syomga'' and Project 671RTM/RTMK ''Shchuka'', (List of NATO reporting names for submarines, NATO reporting names Victor I, Victor II and Victor III, respectively), are ...
– 2 in service, 46 retired
*
Sierra-class submarine
The Sierra class, Soviet designations Project 945 ''Barrakuda'' and Project 945A ''Kondor'', (List of NATO reporting names for submarines, NATO reporting names Sierra I and Sierra II respectively), are a series of Nuclear submarine, nuclear-powe ...
– 4 in service
* – 10 in service, 4 retired
* – 5 in service, 7 ordered
;
People's Liberation Army Navy
The People's Liberation Army Navy, also known as the People's Navy, PLA Navy or simply Chinese Navy, is the naval warfare military branch, branch of the People's Liberation Army, the national military of the People's Republic of China. It i ...
(9 in service)
* – 3 in service, 2 retired
* – 6 in service, 4 ordered
* – 5 ordered
;
Royal Navy
The Royal Navy (RN) is the naval warfare force of the United Kingdom. It is a component of His Majesty's Naval Service, and its officers hold their commissions from the King of the United Kingdom, King. Although warships were used by Kingdom ...
(6 in service)

* – 1 in service, 6 retired
* – 5 in service, 2 ordered
*
SSN-AUKUS – under development (12 planned)
;
French Navy
The French Navy (, , ), informally (, ), is the Navy, maritime arm of the French Armed Forces and one of the four military service branches of History of France, France. It is among the largest and most powerful List of navies, naval forces i ...
(5 in service)
* – 2 in service, 4 retired
*
''Suffren''-class submarine – 3 in service, 3 ordered
;
Royal Australian Navy
The Royal Australian Navy (RAN) is the navy, naval branch of the Australian Defence Force (ADF). The professional head of the RAN is Chief of Navy (Australia), Chief of Navy (CN) Vice admiral (Australia), Vice Admiral Mark Hammond (admiral), Ma ...
(0 in service)
* – 3 ordered
*
SSN-AUKUS – under development (5 planned)
;
Brazilian Navy
The Brazilian Navy () is the navy, naval service branch of the Brazilian Armed Forces, responsible for conducting naval warfare, naval operations.
The navy was involved in War of Independence of Brazil#Naval action, Brazil's war of independence ...
(0 in service)
*
Ãlvaro Alberto – 1 ordered
;
Indian Navy
The Indian Navy (IN) (ISO 15919, ISO: ) is the Navy, maritime and Amphibious warfare, amphibious branch of the Indian Armed Forces. The President of India is the Supreme Commander of the Indian Navy. The Chief of the Naval Staff (India), Chief ...
(0 in service)
* – 1 ordered
*
Project 77-class submarine – under development (6 planned)
Retired SSN classes
;
United States Navy
The United States Navy (USN) is the naval warfare, maritime military branch, service branch of the United States Department of Defense. It is the world's most powerful navy with the largest Displacement (ship), displacement, at 4.5 millio ...
(75 retired, 2 lost)
* – (1954-1980)
* – (1957-1987)
* – 4 in service (1957-1989)
* – 6 in service, 1 lost (1959-1990)
* – (1959-1969)
* – (1960-1976)
* – (1960-1988)
* – 14 in service, 1 lost (1961-1996)
* – 37 in service (1967-2004)
* – (1969-1999)
* – (1974-1990)
;
Soviet
The Union of Soviet Socialist Republics. (USSR), commonly known as the Soviet Union, was a List of former transcontinental countries#Since 1700, transcontinental country that spanned much of Eurasia from 1922 until Dissolution of the Soviet ...
/
Russian Navy
The Russian Navy is the Navy, naval arm of the Russian Armed Forces. It has existed in various forms since 1696. Its present iteration was formed in January 1992 when it succeeded the Navy of the Commonwealth of Independent States (which had i ...
(20 retired, 2 lost)
*
November-class submarine – 14 in service, 1 lost (1959-1991)
*
Alfa-class submarine
The Alfa class, Soviet designation Project 705 Lira (, meaning "Lyre", NATO reporting name Alfa), was a class of nuclear-powered attack submarines in service with the Soviet Navy from 1971 into the early 1990s, with one serving in the Russian Na ...
– 7 in service (1971-1996)
*
K-278 ''Komsomolets'' – lost (1983-1989)
;
Royal Navy
The Royal Navy (RN) is the naval warfare force of the United Kingdom. It is a component of His Majesty's Naval Service, and its officers hold their commissions from the King of the United Kingdom, King. Although warships were used by Kingdom ...
(12 retired)
* – (1963-1980)
* – 2 in service (1966-1994)
* – 3 in service (1970- 1992)
* – 6 in service (1973-2010)
;
Indian Navy
The Indian Navy (IN) (ISO 15919, ISO: ) is the Navy, maritime and Amphibious warfare, amphibious branch of the Indian Armed Forces. The President of India is the Supreme Commander of the Indian Navy. The Chief of the Naval Staff (India), Chief ...
(0 retired, 2 returned)
* was formerly the ''K-43'' leased in 1987 from Russia and returned in 1991.
* was formerly the ''Nerpa'' leased from Russia in 2011 and returned in June 2021.
See also
*
Nuclear submarine
A nuclear submarine is a submarine powered by a nuclear reactor, but not necessarily nuclear-armed.
Nuclear submarines have considerable performance advantages over "conventional" (typically diesel-electric) submarines. Nuclear propulsion ...
*
Ballistic missile submarine
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 capabi ...
(SSB/SSBN)
*
Cruise missile submarine
A cruise missile submarine is a submarine that carries and launches cruise missiles (Submarine-launched cruise missile, SLCMs consisting of land-attack cruise missiles and anti-ship missiles) as its primary armament. Missiles greatly enhance a w ...
(SSG/SSGN)
*
List of submarine classes
*
List of submarine classes of the Royal Navy
This is a list of submarine classes of the Royal Navy of the United Kingdom. Dates of construction given.
Petrol-electric
Diesel-electric
* D class — 8 boats, 1908–1912
* E class — 58 boats, 1912–1916
* F class — 3 boats, 191 ...
*
List of Soviet and Russian submarine classes
Submarines of the Soviet Navy were developed by numbered "projects", which were sometimes but not always given names. During the
Cold War, NATO nations referred to these classes by NATO reporting name
NATO uses a system of code names, called ...
*
List of submarine classes of the United States Navy
References
{{DEFAULTSORT:Ssn (Hull Classification Symbol)
Attack submarines