Ballistic missile submarine A ballistic missile submarine is a submarine equipped to launch submarine - launched ballistic missile s ( SLBMs ) with nuclear warheads . In the US Navy they have the designation SSBN and they are nicknamed ' boomers ' , a common term of art used in everyday briefings and base operations . Virtually all ballistic missile submarines are nuclear powered and are therefore nuclear submarines . History . The world ' s first ballistic missile submarine was a Soviet converted Zulu class submarine equipped with a single ballistic missile launch tube in its sail . The first SSBN class was a Skipjack class fast attack submarine with a missile compartment welded into the middle . Several navies had previously made experimental trials with deck launched missiles . ( See Regulus missile and related articles ) The first nation to field ballistic missile submarines was the Soviet Union . Its first successful submarine launch of a ballistic missile was on 16 September 1955 followed in 1956 by modifying the design of several Zulu class diesel powered attack submarines and installing an extra compartment containing two large vertical ballistic missile launch tubes in the middle with the launchers incorporated in the fin / sail . This was followed by a series of specifically designed Golf class units complemented by the nuclear - powered Hotel class , with both classes having three vertical launch tubes incorporated in the sail / fin of each submarine . The initial SS - N - 4 ballistic missiles could only be launched with the submarines on the surface but were soon followed by SS - N - 5 missiles which were launched with the submarine submerged . The Soviet analogue to the US SSBNs , the Yankee class SSBN with sixteen missiles , began to be built in 1964 . The US Navy fielded the first fleet of its operational missile subs , the George Washington - class submarine in the early 1960s . Purpose . Ballistic missile submarines differ in purpose from attack submarine s and cruise missile submarine s ; while attack submarines specialise in combat with other naval vessels ( including enemy submarines and merchant shipping ) , and cruise missile submarines are designed to attack large warships and tactical targets on land , the primary mission of the ballistic missile is nuclear deterrence . Accordingly , the mission profile of a ballistic missile submarine concentrates on remaining undetected , rather than aggressively pursuing other vessels . Ballistic missile submarines are designed for stealth , to avoid detection at all costs . They use many sound - reducing design features , such as anechoic tile s on their hull surfaces , carefully designed propulsion systems , and machinery mounted on vibration - damping mounts . Ballistic missile submarines equipped with nuclear warheads serve as the third leg of the nuclear triad . The invisibility and mobility of submarines offer both a reliable means of deterrence against an attack ( by maintaining the threat of a second strike ) , and a surprise first - strike capability - particularly given the range of the weapons they carry . Armament . The extra length and / or beam over attack subs of the same generation is in order to accommodate SLBMs such as the Russian R - 29 or the NATO fielded — American manufactured Polaris - II , Poseidon and Trident - II missiles . Although some early models had to surface to launch their missiles , modern vessels typically launch while submerged at keel depth s of usually less than 50 meters ( 164 feet ) . Missiles are launched upwards with an initial velocity sufficient for them to pop above the surface when their rocket motors fire , beginning the characteristic parabolic climb - from - launch of a ballistic missile . Terminology . SSBN is the US Navy hull classification symbol for a nuclear - powered , ballistic missile - carrying submarine . The " SS " denotes " Submarine " , the " B " denotes " ballistic missile , " and the " N " denotes " nuclear powered . " In US naval slang , ballistic missile submarines are called " boomers " . In Britain , they are known as " bombers " . In both cases , submarines operate on a two - crew concept , with two complete crews including two captains , called " Gold " and " Blue " in US , " Starboard " and " Port " in UK . The French Navy commissioned her first ballistic missile submarines as " SNLE " , for " Sous - marin Nucléaire Lanceur d ' Engin " ( lit . " nuclear - powered device - launching submarines " ) . The term applies both to ballistic missile submarines in general ( for instance " British SNLE " occurs ) and , more technically , as a specific classification of the " Redoutable " class . The more recent " Triomphant " class is referred to as SNLE - NG ( " Nouvelle Génération " , " New Generation " ) . The two crews used to maximise the availability time of the ships are called ' blue ' and ' red ' crews . The Soviets called this type of ship RPKSN ( lit . " Strategic Purpose Underwater Missile Cruiser " ) . This designation was applied to the Typhoon class . Another designation used was PLARB ( « ПЛАРБ » - подводная лодка атомная с баллистическими ракетами , which translates as " Nuclear Submarine with Ballistic Missiles " ) . This designation was applied to smaller submarines such as the Delta Class . After a peak in 1984 ( following Able Archer 83 ) , Russian SSBN deterrence patrols have declined to the point where there is less than one patrol per sub each year and at best one sub on patrol at any time . Hence the Russians do not use multiple crews per ship . Accidents . On 4 February 2009 , the British and the French " Le Triomphant " collided in the Atlantic . " Vanguard " returned to Faslane in Scotland , under her own power , and " Triomphant " to Île Longue in Brittany .