Ballistic missile submarine in the context of "USS George Washington (SSBN-598)"

The Armed Forces of the Russian Federation, commonly referred to as the Russian Armed Forces, are the military of Russia. They are organized into three service branches—the Ground Forces, Navy, and Aerospace Forces—three independent combat arms (the Strategic Rocket Forces, Airborne Forces and Unmanned Systems Forces) and the Special Operations Forces Command.

The Russian Armed Forces are the world's fifth largest military force, with about one million active-duty personnel and close to two million reservists. They maintain the world's largest stockpile of nuclear weapons, possess the world's second-largest fleet of ballistic missile submarines, and are the only armed forces outside the United States and China that operate strategic bombers. As of 2024, Russia has the world's third-highest military expenditure, at approximately US$149 billion, or over seven percent of GDP, compared to approximately to US$86.5–$109 billion the year before.

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 informally to refer to remotely operated vehicles and robots, or to medium-sized or smaller vessels (such as the midget submarine and the wet sub). Submarines are referred to as boats rather than ships regardless of their size.

Although experimental submarines had been built earlier, submarine design took off during the 19th century, and submarines were adopted by several navies. They were first used widely during World War I (1914–1918), and are now used in many navies, large and small. Their military uses include: attacking enemy surface ships (merchant and military) or other submarines; aircraft carrier protection; blockade running; nuclear deterrence; stealth operations in denied areas when gathering intelligence and doing reconnaissance; denying or influencing enemy movements; conventional land attacks (for example, launching a cruise missile); and covert insertion of frogmen or special forces. Their civilian uses include: marine science; salvage; exploration; and facility inspection and maintenance. Submarines can be modified for specialized functions such as search-and-rescue missions and undersea cable repair. They are also used in the tourism industry and in undersea archaeology. Modern deep-diving submarines derive from the bathyscaphe, which evolved from the diving bell.

A submarine-launched ballistic missile (SLBM) is a ballistic missile capable of being launched from submarines. Modern variants usually deliver multiple independently targetable reentry vehicles (MIRVs), each of which carries a nuclear warhead and allows a single launched missile to strike several targets. Submarine-launched ballistic missiles operate in a different way from submarine-launched cruise missiles.

Modern submarine-launched ballistic missiles are closely related to intercontinental ballistic missiles (ICBMs), with ranges of over 5,500 kilometres (3,000 nmi), and in many cases SLBMs and ICBMs may be part of the same family of weapons.

In 1952, the United Kingdom became the third country (after the United States and the Soviet Union) to develop and test nuclear weapons, and is one of the five nuclear-weapon states under the Treaty on the Non-Proliferation of Nuclear Weapons. As of 2025, the UK possesses a stockpile of approximately 225 warheads, with 120 deployed on its only delivery system, the Trident programme's submarine-launched ballistic missiles. Additionally, United States B61 nuclear bombs have been stored at RAF Lakenheath since 2025. In 2025, the UK announced plans to procure 12 F-35A aircraft capable of delivering B61s.

Since 1969, the Royal Navy has operated the continuous at-sea deterrent, with at least one ballistic missile submarine always on patrol. Under the Polaris Sales Agreement, the US supplied the UK with Polaris missiles and nuclear submarine technology, in exchange for the general commitment of these forces to NATO. In 1982, an amendment allowed the purchase of Trident II missiles, and since 1998, Trident has been the only nuclear weapons system in British service. Four Vanguard-class submarines are based at HMNB Clyde in Scotland. Each is armed with up to sixteen Trident II missiles, each carrying warheads in up to eight multiple independently targetable re-entry vehicles (MIRVs).

In nuclear strategy, a counterforce target is one that has a military value, such as a launch silo for intercontinental ballistic missiles, an airbase at which nuclear-armed bombers are stationed, a homeport for ballistic missile submarines, or a command and control installation.

The intent of a counterforce strategy (attacking counterforce targets with nuclear weapons) is to conduct a preemptive nuclear strike which has as its aim to disarm an adversary by destroying its nuclear weapons before they can be launched. That would minimize the impact of a retaliatory second strike. However, counterforce attacks are possible in a second strike as well, especially with more survivable submarine-launched weapons like UGM-133 Trident II. A counterforce target is distinguished from a countervalue target, which includes an adversary's population, knowledge, economic, or political resources. In short, a counterforce strike is directed against an adversary's military capabilities, while a countervalue strike is directed against an adversary's civilian-centered institutions.