The Trident missile system is housed on the UK’s four Vanguard class submarines which form the UK’s strategic nuclear missile force.
Each of the four boats are armed with up to 16 Trident II D5 SLBMs, carrying up to 8 warheads each.
The Royal Navy has operated the UK’s Continuous at Sea Deterrent since 1967 when the first SSBN – or Ship Submersible Ballistic Nuclear – HMS Resolution began patrolling armed with the Polaris missile system.
In 1996 HMS Vanguard, the first submarine armed with the Trident missile system, arrived on the Clyde and took over deterrent patrol duties from the Resolution Class. The four Vanguard-class submarines form the UK’s strategic nuclear deterrent force.
Each of the four boats are armed with Trident 2 D5 nuclear missiles. Like all submarines the Vanguard Class are steam powered, their reactors converting water into steam to drive the engines and generate electricity.
It’s often said that the UK’s Trident nuclear weapons system is not ‘independent’ or that the UK doesn’t have the ability to use the system without the US agreeing to it, in reality however that is simply not the case.
Who controls Trident?
One of the most common myths around the system is that the United States has control over the UK’s Trident missile system, that is not the case.
The UK does rely on the US for the heavy maintenance and long term support of the system. For example, the British missiles are serviced at a port in the Georgia, US, and some warhead components are also made in America.
This is why the use of the word ‘operational’ is significant, while the UK can fire without permission, the system would likely not be sustainable without US support beyond a few years.
One common argument is that the US can simply ‘turn off’ the GPS system and therefore can stop the UK using Trident, this is also a myth, Trident isn’t guided by satellite.
The missile uses a kind of stellar sighting guidance system and inertial navigation to take a reading from the stars to work out the missile’s position and make any adjustments necessary. They do not require GPS.
One source for the confusion could be the fact that, aside from those currently deployed, the missiles are held in a communal pool at the US Strategic Weapons facility at King’s Bay, Georgia, USA where maintenance and in-service support of the missiles is undertaken at periodic intervals.
The missiles are jointly maintained, this is much cheaper than the UK doing it on its own and does not give the United States control over any of the weapons deployed on the submarines.
Does the system require American codes to launch?
American operated Trident missiles are controlled through the US Navy chain of command by the US President. ‘Permissive action link technology’ prevents anyone other than the president or someone he has delegated control to authorising a launch.
In 2007, the UK Government revealed that its nuclear weapons were not equipped with Permissive Action Links. Instead, the UK’s nuclear bombs to be dropped by aircraft were armed by just inserting a key into a simple lock similar to those used to protect bicycles from theft, the UK withdrew all air-launched bombs in 1998. The current UK Trident warheads can also be launched by a submarine commander with the support of his crew without any code being transmitted from the chain of command.
The British missiles are controlled through the Royal Navy chain of command all the way up to the Prime Minister. In reality the Prime Minister would make the launch decision in concert with whatever was left of the British government.
The key point here is that the British deterrent does not have permissive action link control, which means it does not rely on the use of codes to fire the system. The UK’s Trident fleet relies purely on military discipline to prevent a launch.
In summary, the UK retains full operational control, to the extent that the US could not stop the UK from using the system, even against the United States.
A Freedom of Information request proving that the United Kingdom has full operational control over its Trident missile system can be downloaded here.