Cruise Missile Submarine (SSGN)

A cruise-missile submarine, US hull symbol SSGN, is a nuclear-powered boat built or converted to deliver a large land-attack cruise-missile salvo. The US Navy converted four Ohio-class SSBNs (Ohio, Michigan, Florida, Georgia) under the early 2000s SSGN program, replacing 22 of the 24 Trident tubes with multiple-all-up-round canisters of up to 154 Tomahawk missiles, plus lock-out capacity for special-operations forces. Russia fields the Oscar II as a large anti-ship-missile SSGN. The G in the symbol denotes guided missile; N denotes nuclear power.