Continuous at sea deterrent

2019 marks the 50th anniversary of the Continuous At Sea Deterrent (CASD). Since April 1969, and the fifth patrol of HMS Resolution, there has always been a Royal Navy Ballistic Missile Submarine at sea, providing the nation’s deterrent and ensuring the UK remains safe.

Generations of Royal Navy Submariners, their families, support workers and industry partners have contributed to the maintenance of CASD, making it a truly national endeavour. 

Today, the United Kingdom’s strategic nuclear deterrent is provided by the Vanguard-class submarine.  The first Vanguard-class – HMS Vanguard – was launched in 1993 and is now the cornerstone of our defence policy and significantly contributes to the Alliance’s deterrent forces.

The Royal Navy maintains an at sea deterrent with one of these submarines at sea all times consecutively and uninterrupted for 50 years, making it the longest ongoing operation ever delivered by the Ministry of Defence.

A credible nuclear deterrent depends upon the ability to threaten an assured and effective response to aggression.  For the Royal Navy, this is done through the Trident D5 Missile

Trident D5 Missiles 

The Trident II D5 missile has a range of over 4,000 nautical miles and an accuracy which can be measured in metres. Each missile is technically capable of delivering up to 12 warheads, enabling a number of different targets to be engaged, and each Vanguard-class submarine has 16 missile tubes. The missile is ejected from the submarine by high-pressure gas and only when it reaches the surface does the rocket system fire.

The Future Deterrent – Dreadnought-Class.

The Dreadnought-class of ballistic submarines are already under construction with the first boat – HMS Dreadnought – expected to come into service in the 2030s.

The four new Dreadnought boats will gradually replace the existing Vanguard-class submarines, carrying on the work of maintaining the Continuous At Sea Deterrent which was begun by the Resolution-class and continuing to ensure our national security far into the future. 

What we are doing

On patrol, 24 hours a day, seven days a week, every day of the year.

Why we are there

Deterring conflict and protecting the nation

Preventing Conflict

The Royal Navy’s presence on the world stage sends a powerful message that the UK is committed to global affairs and provides a stabilising influence. In this way we prevent conflict on the high seas and protect the flow of international trade on which our nation depends.  

Ready to fight

When diplomacy fails, the UK has to be ready to protect its interests and its allies. What’s more, as a member of NATO and the UN, the UK also acts to support the enforcement of UN resolutions and come to the aid of our allies. This is where the Royal Marines come in: we train to go where we’re needed – by sea, land or air – and deploy our forces with the aim of restoring peace.

Location Global

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