The Ministry of Defence is facing a £2.9 billion black hole in its programme to renew Britain’s Trident nuclear weapons system, the National Audit Office has warned.

The National Audit Office (NAO) said the MoD is set to spend £50.9bn over the next 10 years on designing, producing and maintaining the submarines which carry the Trident missiles and their nuclear warheads.

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. Collectively, the submarines and the missiles are informally referred to as the ‘Trident weapons system’ as a whole.

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.

With the programmes, referred to collectively as the Nuclear Estate, accounting for around a quarter of all defence equipment spending over that period, the NAO warned it could “destabilise” the entire equipment plan unless the “affordability gap” was addressed.

The NAO said that the MoD may be forced to make further inroads into the contingency fund, if it is to cover the additional £2.9 billion which it needs to find by 2028.

“Problems with the affordability of the Enterprise could destabilise the department’s overall equipment plan given that around a quarter of its planned spend on equipment relates to nuclear programmes,” the NAO said.

In the current financial year alone, the MoD is forecast to spend £5.2bn across the Nuclear Enterprise, accounting for 14% of the MoD’s total budget.

It includes £1.8 billion on procuring and supporting submarines, £1.4 billion on missiles and warheads, £790 million on propulsion systems, and £220 million on managing the Enterprise.

The concluding remarks of the report, which can be found here:

“Our 2008 report on the nuclear deterrent recommended that the Department address significant risks, particularly around costs, skills, commercial relationships and delivery to schedule. Some of these risks remain 10 years later. In the last 18 months, the Department has made some positive changes to the way it manages the Enterprise and has agreed commercial arrangements designed to improve cost and performance. However, the coming years are crucial.

As the Department invests heavily in the Dreadnought-class submarines and more widely across the Enterprise, it needs to ensure that the new structures, processes and its workforce operate effectively together to maintain the nuclear deterrent. We plan to review aspects of the Enterprise further as these arrangements evolve.”

For the UK Defence Journal, one of the most common myths around the system we have to deal with is the idea 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.