SSN is the United States Navy hull classification symbol for a general-purpose fast attack submarine. The SS denotes a submarine,. and N denotes nuclear power.

History

The US Navy (USN) submarine fleet has been all-nuclear powered for over two decades. The bulk of the USN's SSN fleet has been the Los Angeles-class attack submarine. Designed during the Cold War the Los Angeles class boats' raison d'etre was to protect USN carrier battle groups and to hunt Soviet Navy 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. An Argentinian cruiser, ARA General Belgrano was sunk by torpedoes 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 platforms, intelligence gathering platforms, insertion and exfiltration of special forces 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), higher speed, and extremely quiet operation. Unlike most SSKs, SSNs do not have to surface periodically for air, which would compromise their stealth. These considerations are less significant for modern conventional submarines: LOX and Stirling engine powered vessels can cruise underwater for up to a week and 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 huge expense of building, refuelling and maintaining a nuclear power plant. Nuclear submarines are also a political problem, 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.

The following navies currently operate SSNs:

• United States Navy

• Royal Navy

• Russian Navy

• The Chinese Navy: People's Liberation Army Navy

• The French Navy: Marine Nationale

Active and future SSN classes

United States Navy SSN classes (in service)

• Los Angeles (SSN-688) (some have been retired)

• Seawolf (SSN-21)

• Virginia (SSN-774)

Royal Navy SSN classes (in service)

Known as "Fleet submarines" in the RN

• - First in class, HMS Astute, launched in July 2007

Russian Navy SSN classes (in service)

• Victor III class submarine

• Sierra I and Sierra II class submarines

• Akula class submarine

• Graney class submarine - in development

Marine Nationale SSN classes (in service)

• - in development

People's Liberation Army Navy SSN classes (in service)

• Han class submarine (Type 091)

• Type 093 submarine

• Type 095 submarine - in development

Retired SSN classes

Royal Navy

• HMS Dreadnought (S101) (unique)

• Valiant class submarine

• Churchill class submarine (of which HMS Conqueror was one)

Russian/Soviet Navy

• November class

• Mike class - the ill-fated K-278 Komsomolets

• Alfa class

United States Navy

• (unique)

• (unique)

• Skate (SSN-578)

• Skipjack (SSN-585)

• USS Triton (SSN-586) (unique)

• USS Halibut (SSN-587)

• USS Thresher/Permit (SSN-593)

• (unique)

• Sturgeon (SSN-637)

• (unique)

• (unique)

See also

• SS

• SSB/SSBN

• SSG

• SSGN

• List of submarine classes

• List of submarine classes of the Royal Navy

• List of Soviet and Russian submarine classes

• List of United States submarine classes