Since April 1969 the United Kingdom has operated a continuous at sea nuclear deterrent meaning somewhere in the ocean a British nuclear armed submarine has been on patrol.

Though this was not always the case as for years before it was a deterrent operated by the Royal Air Force through the V-bomber force but there was a good reason for this switch.

Simply put it is easier to hide a submarine in the some 300+ million cubic metres of water of the world’s oceans than what is in comparison the tiny land mass of the UK for an aircraft.

As bombers need runways, hangars, barracks and generally a large amount of support thought that is not to say a submarine does not need this.

But a runway and airbase is easy to find, it cannot be hidden from prying eyes who would potentially attack it and doing so would disable our nuclear deterrent; this is not a threat a submarine would face.

As while the Faslane base could be attacked and destroyed in a pre-emptive strike that would not affect the submarine that is on patrol, meaning that unless you have tracked all the submarines it is invulnerable which provides an ‘assurance of retaliation’.

Though that will only work with a minimum number of submarines and that is what we have, 4 submarines, any less and it would risk being not continuous meaning its credibility is lost and the deterrent fails.

The question here is why 4 submarines is the minimum? Why not three or two? Simply put no machine that man can make is infallible, everything can break. So if the submarine on patrol were to suffer a fault, we would need one to put to see immediately to resume the patrol as the former came in for repair.

Though it is not just about the submarine carrying the missiles but the missiles themselves that determine if a deterrent is credible. These are usually determined by the missile range and the warhead load of the missile and back when the purchase of Polaris was occurring, these were huge determining factors.

As the size of the deterrent will determine what you get operationally, if we wanted a 10 or 20 city deterrent would determine if we needed 4 or 5 submarines as each could carry 16 missiles equipped with 3 warheads each.

So with one submarine at sea you could have a potential of 48 warheads but the consideration of anti-ballistic missile defences were in mind, so not all 48 would penetrate and hit a target and many cities would need multiple warheads.

But all of this costs and its costs huge sums of money, not just to purchase a 5th submarine and more missiles. But to crew and maintain this submarine, to purchase and maintain the extra missiles and warheads needed to load it, the support staff and chain needed at base.

Now in the 21st century, missile and warhead counts on submarines are being reduced owing to the Non-Proliferation Treaty though counterbalanced by more powerful and destructive missiles and warheads.

With all this, we are here in June 2017 with plans in place to renew the deterrent, to purchase 4 new submarines (the Dreadnought Class) to replace the current Vanguard Class. Yet this will be a like for like replacement, no more submarines, nor warheads; the latest iteration of the same basic policy.

So both politically and financially there is a balancing act to maintain the continuous at sea nuclear deterrent but this just means it is there not that it is operational.

In the coming week we shall look at what it takes to keep the deterrent in place, the policy and military doctrine behind it; as possessing nuclear weapons is just the first step to a nuclear deterrent.

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4 Subs gives 1 on patrol, 1 preparing, 1 in refit and 1 spare. 5 gives 2 subs on patrol, a much better option, something which the RN has managed from time to time, much to the USN’s surprise and admiration.


Yea two crews lots of time off and a huge amount of money wasted.

Have 3 boats and longer patrols


Longer patrols might put people off being part of it.


Bobo, you couldn’t do it with 3 with the maintenance periods these boats need. Not to mention supplies and not seeing daylight for 6 months as you suggest! You’d get nobody going to sea. 3-3.5 months of no daylight and not being able to speak to family is enough for anybody!


Or if it was up to Corbyn – 1 on patrol, 1 preparing, 1 in refit, 1 in reserve….. and not a missile amongst them!!


It was never up to Corbin may i suggest before you make statements you check facts Labour policy is to maintain our nuclear deterrent.

Richard Kimber

David said “…if it was up to Corbyn”, he didn’t mention labour!
If it was up to Corbyn we wouldn’t have nuclear weapons, he has been a staunch and vocal member of CND for decades.
Swansea1962 I suggest you properly read and attempt to comprehend people comments before shouting them down.


Thank you Richard – spot on my friend!


‘…if it was up to Corbyn”, he didn’t mention labour!’ – he doesn’t really need to, does he ? In any case it’s reasonable to point out what Labour party policy is, and that is to retain it, just to make things clear. After all, it was Labour who created the British deterrent.


Good reply


Waste of money, a few nuclear tipped Cruise missiles both Submarine & Air launched more then enough for us. we aren’t a super power , we only need a deterrent not a 100 billion white elephant.


Cruise missiles can be shot down.


It’s less that and more this. In modern combat people throw around lots of cruise missiles. If your enemy (or say a foreign power you haven’t always seen eye to eye with) throws around cruise missles then you get very twitchy knowing that their only/primary delivery method for nuclear warheads is said cruise missile.

Ballistic misdiles are very obvious about what they are. You cannot really disguise them as another weapon so foreign powers are a lot more comfortable being next door to a conventional engagement if they know that your only delivery method is an ICBM.


Good point.

Nick Bowman

It’s not about warhead numbers. The U.K. chooses to arm each missile with far fewer warheads (multiple independent re-entry vehicles) than its capacity. It’s a minimum credible deterrent. Personally, I’m troubled by the lack of political discussion about the advancement of anti-ballistic missile technology. I think the “successor” class will be the last U.K. SSBNs because fifty years from now the missiles will be too vulnerable to interception.


I think that’s true. Nuclear disarmament won’t come about from political will and treaties, it is ABM technology that will make the likelihood of a missile getting through too remote to be a real deterrent any more. In theory the effects of pretty much rock-solid ABM defences could go two ways though, either the nuclear powers decide that SSBN is no longer worth it because of the low probability of “success” (if you can call it that) and disarm or, in an alternative dystopian future, nuclear-armed nations decide that saturation attacks are the answer and the proliferation of warheads and… Read more »