Submarines had a critical role during World War II in the defense of America, and other countries, against Japanese naval ships. They can operate under water and therefore are invisible to enemy ships. They can also perform blockade running and reconnaissance missions. They can also be used to salvage missions.
The United States Navy currently has three types of attack submarines. These vessels are equipped for engaging an enemy vessel, and are sometimes referred to as "boomers". The ballistic missile submarines can carry nuclear warheads without detection and deliver them to their targets. The United States Navy will possess approximately 66 submarines by 2030. The submarine fleet will actually be the third largest worldwide.
The United States Navy currently possesses 14 ballistic-missile submarines, (SSBNs), and four nuclear-powered attack submarines (SSGNs). SSBNs can carry nukes for extended patrols. SSGNs are also capable of carrying Special Forces insertion or strike capability. Each SSBN has two crews. Each SSBN can carry about 24 SLBMs. SSBNs last approximately 42 years. They can spend up to 77 days at sea.
The United States Navy operates three classes: surveillance, combat, support for on-shore operations and Virginia. The newer Seawolf and Virginia classes are optimized for the post-Cold War threat environment. These submarines can carry Trident II D5 rockets for greater range and accuracy.
The United States Navy has a 30-year-old shipbuilding plan. This will allow for an increase in the submarine fleet of four boats per year or about ten per year. These boats are used to attack targets, conduct reconnaissance, and conduct blockade running. The Navy will eventually have 93 submarines.
The US Navy has opposed the export of diesel-electric submarines for many years. There are currently eight submarines in the United States, five in Japan, and two in Taiwan. The United States Navy is equipped with nuclear-powered submarines. These are fuelled using high-enriched Uranium. Over 6200 reactor years of incident-free experience has been accumulated by the United States Navy. They are also used in support of research and marine sciences.
The United States Navy has four classes of attack submarines. The SSN(X), the next generation of submarines will combine the speed and stealth characteristics of the Seawolf and Virginia classes. These submarines will come equipped with advanced sensors, and will be able cooperate with a larger group of off-hull vehicles. SSN(X) is the Navy's new program. It aims to reorient United States undersea combat capabilities towards a greater power competition.
The United States Navy will keep having nuclear-powered subs in the future. It plans to have 66 total submarines by 2030. The United States Navy plans to continue operating a total of 81/81 nuclear-powered ships in 2017. Between major overhauls, the submarines will be in service for around 15 years. The US Navy has three sub-classes of submarines, none of which are nuclear-powered. These submarines are useful for tourism, salvage, and archaeology.