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.