Britain's only nuclear deterrent submarine fleet.

The four Vanguard-class ballistic missile submarines, carrying missiles equivalent to 120 million tons of TNT, constitute Britain's sole nuclear deterrent.

Vanguard-class submarine returns to port after patrol.

The British Navy maintains a fleet of four Vanguard-class strategic submarines equipped with powerful nuclear ballistic missiles capable of wiping out the world's largest nations. This is the only nuclear deterrent force in the British military's inventory for the past 50 years, according to National Interest.

In the early 1960s, the British nuclear deterrent force was built on the foundation of a trio of strategic bombers called the "V-Force," consisting of the Avro Vulcan, Handley Page Victor, and Vickers Valiant. These were equipped with the American-made GAM-87 Skybolt air-launched ballistic missiles, capable of penetrating Soviet defenses thanks to their speeds of up to 15,300 km/h. However, the Skybolt missile suffered from too many technical flaws, leading the US government to cancel the project in 1962.

The US halting the Skybolt program deprived the UK of its nuclear deterrence capability, forcing the two countries to jointly seek a solution. Washington proposed using UGM-27 Polaris submarine-launched ballistic missiles (SLBMs) ​​to replace Skybolt. To implement this solution, the UK would have to build strategic submarines capable of carrying ballistic missiles.

The British Ministry of Defence estimated that the country needed at least five Polaris-class strategic missile submarines to maintain a credible nuclear deterrent. London later reduced this number to four. The first solution was the Resolution-class submarine, designed based on the US Navy's Lafeyette-class ballistic missile submarine. Each submarine has two missile launch tubes with a total of 16 missiles located behind the command bridge.

The submarines were all built in Britain, but used American missiles, launch tubes, and fire control systems. Each was equipped with 16 Polaris A-3 missiles with a range of 4,025 km, each carrying a British-made nuclear warhead. The upgraded Polaris A-3TK version was later fitted with six independent Chevaline warheads, each with a destructive power equivalent to 150,000 tons of TNT or 10 atomic bombs dropped on Hiroshima.

HMS Resolution was the first of the Resolution class, commissioned in 1967 andThe Polaris rocket was first successfully test-fired in January 1968 off the coast of Florida, USA.The next three submarines were commissioned between 1968 and 1969.

The submarine HMS Vigilant before setting sail. Photo: SeaForce.

In the early 1980s, the Resolution-class ships became obsolete and needed replacing. Britain decided to build four new Vanguard-class ships, continuing to equip them with the American Trident nuclear missiles. The first, HMS Vanguard, entered service in 1993, followed by HMS Victorious in 1995, HMS Vigilant in 1996, and HMS Vengeance in 1999. The Vanguard successfully test-fired a Trident II ballistic missile in 1994, before beginning combat patrols a year later.

With a displacement of 15,000 tons, the Vanguard-class submarines are twice the size of the preceding Resolution-class submarines. The design included 16 SLBM launch tubes, but the British Ministry of Defence decided to equip each submarine with only 8 Trident II D-5 missiles with a range of 7,400 km.

Each Trident II D-5 missile can carry up to eight warheads with a total explosive yield equivalent to 3.8 million tons of TNT. This allows a single Vanguard-class submarine to carry the equivalent of 30 million tons of TNT, or 2,000 bombs dropped on Hiroshima. In total, a fleet of four Vanguard submarines would be equipped with warheads equivalent to 120 million tons of TNT, enough to wipe out any nation in the world.

Each class submarineVanguardThey are assigned two crews who take turns to maintain combat readiness. In the Continuous Sea Deterrence Scheme (CASD), Britain always has at least one Vanguard-class submarine on patrol at any given time, one submarine finishes its patrol to prepare for rest, another is ready to go out to sea to replace it, while a fourth is undergoing maintenance. For the past 48 years, a British submarine has been patrolling the seas every single day.

A Vanguard-class submarine test-fires a Trident ballistic missile.

In September 2016, the British Navy began construction of the Successor submarine, the first of the new generation Dreadnought-class, with a displacement of 17,200 tonnes. Each submarine will be equipped with 12 launch tubes, reusing Trident D-5 missiles from the Vanguard class.

The Dreadnought-class ships are expected to be commissioned in the 2030s and serve until the 2060s. The UK Ministry of Defence estimates it will cost $39 billion to operate this fleet for 35 years, plus approximately $12 billion in contingency costs.

By maintaining a fleet of four submarines carrying SLBMs, Britain ensures it has at least 64 nuclear warheads always at sea, ready to launch an attack within minutes. This is a sufficient amount of strategic weaponry to deter and prevent any adversary from launching a preemptive strike against London, military expert Kyle Mizokami stated.

According to VNE