Trident (UK nuclear programme)

The Trident programme was initiated during the Cold War, and it was designed to provide an ongoing independently controlled deterrent against major threats to the security of the UK and its NATO allies, including threats posed by non-nuclear weapons.[65]

To provide an effective deterrent, the Trident system was intended to "pose a potential threat to key aspects of Soviet state power" whilst being invulnerable to a surprise or pre-emptive nuclear strike. As with Polaris, Trident was owned and operated by the UK but committed to NATO and targeted in accordance with plans set out by the organisation's Supreme Allied Commander Europe, who is traditionally a senior figure in the US military.[66] Under the terms of the Polaris Sales Arrangement, the US does not have a veto on the use of British nuclear weapons, which the UK may launch independently,[67] but this would only occur if "supreme national interests" required it.[66]

The final decision on firing the missiles is the responsibility of the prime minister, who, upon taking office, writes four identical letters of last resort, one of which is locked in a safe on board each of the Vanguard-class submarines. If contact with the UK is lost, the commanding officer of a submarine has to follow the instructions in the letter if they believe that the United Kingdom has suffered an overwhelming attack. Options include retaliating with nuclear weapons, not retaliating, putting the submarine under the command of an ally or acting as the captain deems appropriate. The exact content of the letters is never disclosed, and they are destroyed without being opened upon a new prime minister taking office.[68]

By the time of the first Vanguard patrol in December 1994, the Soviet Union no longer existed, and the government adjusted its nuclear policy in the following years.[25] Trident's missiles were "detargetted" in 1994 ahead of Vanguard's maiden voyage.[69] The warheads are not aimed at specific targets but await co-ordinates that can be programmed into their computers and fired with several days' notice.[1][25]

Under the terms of the 1987 Intermediate-Range Nuclear Forces Treaty with the Soviet Union, the US withdrew its surface naval nuclear weapons and short-range nuclear forces. The GLCMs were withdrawn from the UK in 1991,[70] and the Polaris submarine base at Holy Loch was closed in 1992.[71] The last US warheads in British service under Project E, the B57 nuclear depth bombs and the Lance missiles and W48 nuclear artillery shells used by the British Army of the Rhine, were withdrawn in July 1992.[70] The British Conservative government followed suit. The deployment of ships carrying nuclear weapons caused embarrassment during the Falklands War, and in the aftermath it was decided to stockpile them ashore in peacetime.[72] The nuclear depth bombs were withdrawn from service in 1992,[73][74] followed by the WE.177 free-fall bombs used by the Royal Navy and RAF on 31 March 1998.[75] This left Trident as Britain's sole nuclear weapons system.[25]

Although Trident was designed as a strategic deterrent, the end of the Cold War led the British government to conclude that a sub-strategic—but not tactical—role was required, with Trident missiles assuming the role formerly handled by the RAF's WE.177 bombs.[76] The 1994 Defence White Paper stated: "We also need the capability to undertake nuclear action on a more limited scale in order to ... halt aggression without inevitably triggering strategic nuclear exchanges". A later statement read: "We also intend to exploit the flexibility of Trident to provide the vehicle for both sub-strategic and strategic elements of our deterrent … as an insurance against potential adverse trends in the international situation".[77] On 19 March 1998, the Defence Secretary, George Robertson, was asked to provide a statement "on the development of a lower-yield variant of the Trident warhead for the sub-strategic role". He replied, "the UK has some flexibility in the choice of yield for the warheads on its Trident missiles".[78]

The UK has not declared a no first use policy regarding launching a nuclear attack; former British defence secretary Geoff Hoon stated in 2002 and 2003 that the UK would be willing to attack rogue states with them if nuclear weapons were used against British troops.[79][80] In April 2017 Defence Secretary Michael Fallon confirmed that the UK would use nuclear weapons in a "pre-emptive initial strike" in "the most extreme circumstances".[81] Fallon stated in a parliamentary answer that the UK has neither a 'first use' or 'no first use' in its nuclear weapon policy so that its adversaries would not know when the UK would launch nuclear strikes.[82]

In March 2021, the UK suggested a shift in nuclear policy in its Integrated Defence Review, stating that the UK would reserve the right to use nuclear weapons in the face of weapons of mass destruction, which includes "emerging technologies that could have a considerable impact", including cyber technologies, to chemical or biological weapons.[83] This marks a shift from existing UK policy, in that nuclear weapons would only be launched against another nuclear power or in response to extreme chemical or biological threats.[84] It did, however, stress that the UK would not use or threaten to use nuclear weapons against any non-nuclear weapon party to the Treaty on the Non-Proliferation of Nuclear Weapons 1968, but only if the state is not in "material breach" of the Treaty's obligations.[83] The shift in language comes after the UK lifted the cap on the number of Trident nuclear warheads it can stockpile by 40% from 180 to 260 warheads "in recognition of the evolving security environment".[85][86] The UK has also stated it would no longer declare how many deployable warheads it has in a new policy of deliberate ambiguity.[85] The move is intended to cement the UK's status as a nuclear power and a US defence ally.[86][87] Labour Party Leader Keir Starmer, although supporting nuclear deterrence, criticised the new policy and questioned why Prime Minister Boris Johnson believed that increasing the stockpile was necessary.[88][89] Kate Hudson of the Campaign for Nuclear Disarmament warned against the start of a "new nuclear arms race".[85]

HMS Vanguard leaves HMNB Clyde in Scotland.

Four Vanguard-class submarines were designed and built at Barrow-in-Furness by Vickers Shipbuilding and Engineering, now BAE Systems Submarines, the only shipbuilder in the UK with the facilities and expertise to build nuclear submarines. Even so, £62 million worth of new shipbuilding and dock facilities were added for the project,[90] with the Devonshire Dock Hall built specially for it.[91] The initial plan was to build new versions of the Resolution-class, but in July 1981 the decision was taken to incorporate the new Rolls-Royce PWR2 pressurised water reactor. From the outset, the Vanguard submarines were designed with enlarged missile tubes able to accommodate the Trident II D-5. The missile compartment is based on the system used on the American Ohio class, although with capacity for only 16 missiles, rather than the 24 on board an Ohio boat. The boats are significantly larger than the Resolution class, and were given names formerly associated with battleships and aircraft carriers, befitting their status as capital ships.[92] An important consideration was the depth of the Walney Channel, which connected Barrow to the Irish Sea, which limited the draft to 27+1⁄2 feet (8.4 m), while the Ohio-class boats had a draft of 33 feet (10 m).[90] Each boat is 150 metres (490 ft) long and 13 metres (43 ft) in diameter, and carries a crew of 150 officers and ratings.[93]

The submarines use a tactical-information and weapons-control system called the Submarine Command System Next Generation.[94] This system was developed in collaboration with Microsoft,[95] and is based on the same technology as Windows XP, which led the media to give it the nickname "Windows for Submarines", with the UK Defence Journal fact checking group countering claims the vessels run on Windows XP.[96] In addition to the missile tubes, the submarines are fitted with four 21-inch (533 mm) torpedo tubes and carry the Spearfish torpedo,[97] allowing them to engage submerged or surface targets at ranges up to 65 kilometres (40 mi; 35 nmi). Two SSE Mark 10 launchers are also fitted, allowing the boats to deploy Type 2066 and Type 2071 decoys, and a UAP Mark 3 electronic support measures (ESM) intercept system is carried. A "Core H" reactor is fitted to each of the boats during their long-overhaul refit periods, ensuring that none of the submarines will need further re-fuelling.[98]

Thatcher laid the keel of the first boat, HMS Vanguard, on 3 September 1986,[91] and it was commissioned on 14 August 1993. She was followed by her sisters, HMS Victorious, which was laid down on 3 December 1987 and commissioned on 7 January 1995; HMS Vigilant, which was laid down on 16 February 1991 and commissioned on 2 November 1996; and HMS Vengeance, which was laid down on 1 February 1993 and commissioned on 27 November 1999.[98] The first British Trident missile was test-fired from Vanguard on 26 May 1994, and she began her first patrol in December of that year. According to the Royal Navy, at least one submarine has always been on patrol ever since.[99]

Models of the black warhead re-entry vehicles on a Trident missile at the National Museum of Nuclear Science & History in New Mexico

In British service, Trident II missiles are fitted with a thermonuclear warhead called Holbrook.[100] The warhead has a choice of two warhead yields[101] the highest of which is thought to be 100 kilotons of TNT (420 TJ), with a lower yield in the range of 0.3 to 10 kilotons of TNT (1.3 to 41.8 TJ).[102] The UK government was sensitive to charges that the replacement of Polaris with Trident would involve an escalation in the numbers of British nuclear weapons. When the decision to purchase Trident II was announced in 1982, it was stressed that while American Trident boats carried 24 missiles with eight warheads each, a total of 192 warheads, British Trident boats would carry no more than 128 warheads—the same number as Polaris. In November 1993, the Secretary of State for Defence, Malcolm Rifkind, announced that each boat would deploy no more than 96 warheads.[71] In 2010 this was reduced to a maximum of 40 warheads, split between eight missiles.[93][1] The consequent reduction in warhead production and refurbishment was estimated to save £22 million over a ten-year period.[103] However in 2021 the Boris Johnson announced that the total number of warheads was being lifted from 180 to 260.[104]

The warheads are primarily constructed at AWE Aldermaston, with other parts being made at other AWE facilities such as Burghfield.[105] The British government insists the warhead is indigenously designed, but analysts including Hans M. Kristensen with the Federation of American Scientists believe that it is largely based on the US W76 design.[100][106] Under the 1958 US–UK Mutual Defence Agreement the UK is allowed to draw upon US warhead design information, but constructing and maintaining warheads for the Trident programme is the responsibility of AWE.[25] US President George H. W. Bush authorised the transfer of nuclear warhead components to the UK between 1991 and 1996.[107] The first Holbrook warhead was finished in September 1992 with production probably ending in 1999.[102] Each warhead is housed in a cone-shaped re-entry vehicle made in the US called the Mk 4 and is the same reentry vehicle used by the US Navy with its W76 warhead.[108] This shell protects it from the high temperatures experienced upon re-entry into Earth's atmosphere.[109] The Trident warhead's fusing, arming and firing mechanisms are carefully designed so that it can only detonate after launch and ballistic deployment.[110] On 25 February 2020, the UK released a Written Statement outlining that the current UK nuclear warheads will be replaced and will match the US Trident SLBM and related systems.[111] Earlier, it was reported that Commander US Strategic Command, Admiral Charles Richard, mentioned in a Senate hearing that the UK was already working to replace its warheads, matching the future US W93 warhead.[112]

As of 2016, the UK had a stockpile of 215 warheads, of which 120 are operationally available.[113] In 2022 the UK Government announced that "the UK will move to an overall nuclear weapon stockpile of no more than 260 warheads."[114] British SSBNs on patrol carried a maximum of 40 warheads and 8 missiles.[115] In 2011 it was reported that British warheads would receive the new Mk 4A reentry vehicles and some or all of the other upgrades that US W76 warheads were receiving in their W76-1 Life Extension Program.[116] Some reports suggested that British warheads would receive the same arming, fusing and firing system (AF&F) as the US W76-1.[117] This new AF&F system, called the MC4700, would increase weapon lethality against hard targets such as missile silos and bunkers.[118] Due to the distance of 720 km (450 mi) between AWE Aldermaston and the UK's nuclear weapon storage depot at RNAD Coulport, Holbrook (Trident) warheads are transported by road in heavily armed convoys by Ministry of Defence Police.[119] According to a pressure group, between 2000 and 2016 the vehicles were involved in 180 incidents, ranging from delays and diversions because of accidents, protests, or bad weather, to a sudden loss of power in one of the lorries, which halted a convoy and caused a double lane closure and a tailback on the M6 motorway. The group's analysis stated the incidents were more frequent in the years 2013–2015.[120]

Test launch of a Trident II missile

Trident II D-5 is a submarine-launched ballistic missile built by Lockheed Martin Space Systems in Sunnyvale, California, and deployed by the US Navy and the Royal Navy.[121] The British government contributed five per cent of its research and development costs under the modified Polaris Sales Agreement. The development contract was issued in October 1983, and the first launch occurred in January 1987. The first submarine launch was attempted by USS Tennessee in March 1989. This attempt failed because the plume of water following the missile rose to a greater height than expected, resulting in water being in the nozzle when the motor ignited. Once the problem was understood, simple changes were quickly made, but the problem delayed the entry into service of Trident II until March 1990.[122]

Trident II D-5 is more sophisticated than its predecessor, Trident I C-4, and has a greater payload capacity. All three stages of the Trident II D-5 are made of graphite epoxy, making the missile much lighter than its predecessor.[123] The first test from a British Vanguard-class submarine took place in 1994.[124] The missile is 13 metres (43 ft) long, weighs 58.5 tonnes (129,000 lb), has a range of 11,300 kilometres (7,000 mi), a top speed of over 21,600 km/h (13,400 mph) (Mach 17.4) and a circular error probable (CEP) accuracy to within "a few feet".[125] It is guided using an inertial navigation system combined with a star tracker, and is not dependent on the American-run Global Positioning System (GPS).[1]

The 1998 Strategic Defence Review announced that the number of missile bodies would be limited to the 58 already purchased or under order, and the Royal Navy would not receive the final seven missiles previously planned.[126] This saved about £50 million.[103] The UK missiles form a shared pool with the Atlantic squadron of the US Navy Ohio-class SSBNs at Kings Bay. The pool is "co-mingled" and missiles are selected at random for loading on to either nation's submarines.[127][128] The first Trident boat, HMS Vanguard, collected a full load of 16 missiles in 1994, but Victorious collected only 12 in 1995, and Vigilant, 14 in 1997, leaving the remaining missile tubes empty.[129]

By 1999, six missiles had been test fired, and another eight were earmarked for test firing.[130] In June 2016, a Trident II D-5 missile "veered off in the wrong direction towards America" after being launched from Vengeance off the coast of Florida.[127][131] The incident was not revealed until January 2017; the Sunday Times reported that Downing Street had "covered up" the incident "just weeks before the crucial House of Commons vote on the future of the missile system."[132] Subsequent media reports said this was at the request of the US.[133] Successful Royal Navy test firings had occurred in 2000, 2005, 2009 and 2012. They are infrequent due to the missile's £17 million cost.[134] By August 2016 there had been 161 successful test firings of the Trident II D-5 missile since 1989, the most recent being from USS Maryland in August 2016.[135] Fewer than 10 test flights have been failures,[136] and the Royal Navy is not known to have had a previous failure.[137]

In the 1990s, the total acquisition cost of the Trident programme was £9.8 billion, about 38 per cent of which was incurred in the US. In 2005–06, annual expenditure for the running and capital costs was estimated at between £1.2 billion and £1.7 billion and was estimated to rise to £2bn to £2.2 billion in 2007–08, including Atomic Weapons Establishment costs. Since Trident became operational in 1994, annual expenditure has ranged between 3 and 4.5 per cent of the annual defence budget, and was projected to increase to 5.5 per cent of the defence budget by 2007–08.[138][139] An important factor in the cost was the exchange rate between the dollar and the pound, which declined from $2.36 in September 1980 to $1.78 in March 1982.[92]

The principle of Trident's operation is known as Continuous At-Sea Deterrence (CASD), which means that at least one submarine is always on patrol.[140] Another submarine is usually undergoing maintenance and the remaining two are in port or on training exercises. During a patrol, the submarine is required to remain silent and is allowed to make contact with the UK only in an emergency. It navigates using mapped contour lines of the ocean floor and patrols a series of planned "boxes" measuring several thousand square miles. A 1,000-metre-long (3,300 ft) aerial trails on the surface behind the submarine to pick up incoming messages. Most of the 150 crew never know where they are or where they have been.[141] The 350th patrol commenced on 29 September 2017.[142][143] On 15 November 2018, a reception was held at Westminster to mark 50 years of CASD.[144]

Only the prime minister or a designated survivor can authorise the missiles to be fired.[145] These orders would likely be issued from the Pindar command bunker under Whitehall in central London. From there, the order would be relayed to the Commander, Task Force 345 (CTF 345) operations room at the Northwood Headquarters facility in Hertfordshire, the only facility allowed to communicate with the Vanguard commander on patrol.[146] Communications are relayed via IP over VLF from a transmitter site at Skelton near Penrith.[147] Two personnel are required to authenticate each stage of the process before launching, with the submarine commander only able to activate the firing trigger after two safes have been opened with keys held by the ship's executive and weapon engineer officers.[148] A parliamentary answer states that commanding officers of Royal Navy ballistic submarines receive training in the 'Law Of Armed Conflict'.[145]

HMS Vigilant alongside No. 10 berth at HM Naval Base (HMNB) Clyde in October 2007

Trident is based at HMNB Clyde on the west coast of Scotland. The base consists of two facilities — Faslane Naval Base on Gare Loch near Helensburgh, and an ordnance depot with 16 concrete bunkers set into a hillside at Coulport, 4 km (2.5 mi) to the west. Faslane was constructed and first used as a base during the Second World War. This location was chosen as the base for nuclear-armed submarines at the height of the Cold War because of its position close to the deep and easily navigable Firth of Clyde. It provides for rapid and stealthy access through the North Channel to the patrolling areas in the North Atlantic, and through the GIUK gap between Iceland and Scotland to the Norwegian Sea. Also based there are Astute-class nuclear-powered fleet submarines (SSNs).[149][150] RNAD Coulport is used to store the nuclear warheads and has docking facilities where they are loaded onto submarines before going on patrol and unloaded when they return to the base.[151] Repair and refit of the Vanguard-class submarines takes place at HMNB Devonport near Plymouth, Devon.[152]

According to senior RAF officers the retirement of the Nimrod maritime patrol aircraft in 2011 gave Russia the potential to gain "valuable intelligence" on the country's nuclear deterrent. As a result, plans to buy Northrop Grumman MQ-4C Triton unmanned aerial vehicles were reportedly considered.[153][154] The Strategic Defence and Security Review 2015 announced that nine Boeing P-8 Poseidon maritime patrol aircraft would be purchased for the RAF.[115] They became operational on 3 April 2020.[155]

The Royal United Services Institute (RUSI), a British defence and security think tank, released a paper in July 2010 assessing four possible options for maintaining both an effective nuclear deterrent and also reducing costs in light of anticipated budget restrictions.[167] These proposals were motivated by the fact that funding for the Trident renewal programme now had to come from the core Ministry of Defence budget.[168] Four alternatives were considered: Trident submarines on continuous patrol; Trident submarines not on patrol continuously; attack submarines armed with nuclear cruise missiles; and land-based nuclear weapons.[167] The paper concluded that "given the opportunity costs for conventional capabilities that current plans for Trident renewal are due to incur over the next decade...there is now a growing case for a re-examination of whether there are less expensive means of pursuing this objective. A key element of such a review is likely to be a reconsideration of the need to maintain a commitment to CASD in strategic circumstances that are now very different from those in which it was first introduced."[169]

The 2013 Trident Alternatives Review was an 18-month study led by the Cabinet Office that was aimed at establishing whether or not there were credible alternatives to the UK's submarine-based CASD. Accordingly, the review analysed a range of delivery systems and warhead designs with respect to their affordability and effectiveness against potential targets.[170] Ultimately, the Trident Alternatives Review came to the conclusion that there were alternatives to Trident that "would enable the UK to be capable of inflicting significant damage such that most potential adversaries around the world would be deterred", but none would "offer the same degree of resilience as the current posture". The review asserted that whether or not cruise missile-based systems offer a credible alternative was contingent upon a political judgement on whether the UK could accept a "significant increase in vulnerability" and a reduction in who it could deter.[170]

The publication of the report was met with a mixed reception from different political parties and non-governmental organisations (NGOs) in the field of non-proliferation and disarmament. While it was welcomed by the prime minister, David Cameron, as having confirmed the necessity of like-for-like replacement of Trident, Liberal Democrat cabinet minister Danny Alexander deemed it a demonstration of the fact there are "credible and viable alternatives to the UK's current approach to nuclear deterrence." NGOs including the British American Security Information Council (BASIC), a non-proliferation and disarmament think-tank, criticised the report for its limited scope and its failure to engage with a wider array of considerations related to nuclear weapons, including environmental and humanitarian issues.[171][172]

In 2011, BASIC launched an independent cross-party Commission to initiate a deeper national debate on the UK's nuclear weapons policy and examine questions around the contentious issue of Trident renewal. The Commission operated under the chairmanship of former Labour Secretary of State for Defence, Lord Browne of Ladyton; former Conservative Defence and Foreign Secretary, Sir Malcolm Rifkind; and Sir Menzies Campbell, former leader of the Liberal Democrats and Shadow Foreign Secretary.[173] After three years' of deliberation, the Commission released its final report on 1 July 2014. It suggested, with important caveats, that the UK should retain a nuclear deterrent. The conclusion acknowledged that "it remains crucial that the UK show keen regard for its position within the international community and for the shared responsibility to achieve progress in global nuclear disarmament."[174]

BASIC's interpretation of the report also focused on this point, emphasising that the commissioners "agreed that the health of the global strategic environment, particularly nuclear non-proliferation, is critical to national security and is a central consideration. They talk of the need for Britain to maintain its 'glide path down towards disarmament', to ensure that the renewal decisions the next government will be taking have consistency with the trajectory set by successive recent governments, and that the UK should continue to be 'at the forefront of the multilateral disarmament process.'"[175]

The Vanguard-class submarines were built with a 25-year life expectancy, taking them into the 2020s. Trident II D-5 missiles are expected to continue in service until at least 2040 following an upgrade.[176] A December 2006 Ministry of Defence white paper, entitled "The Future of the United Kingdom's Nuclear Deterrent", recommended that the nuclear weapons should be maintained and outlined measures that would do so until the 2040s. It advocated the currently preferred submarine-based system, as it remained the cheapest and most secure deterrence option available. Costs for this option are estimated at £15–20 billion based on:

• £0.25 billion to participate in US Trident D-5 missile life extension programme.
• £11–14 billion for a class of four new SSBNs.
• £2–3 billion for refurbishing warheads.
• £2–3 billion for infrastructure.[177]

These 2006/07 prices would equate to about £25bn for the Successor-class submarines as they were provisionally named; the 2011 Initial Gate report confirmed estimates of £2-3bn each for the warheads and infrastructure.[178] These cost estimates exclude the Vanguard five-year life extension and decommissioning, and it is unclear if new Trident missiles will need to be purchased for the life extension programme.[179] Running costs would be about £1.5 billion per year at 2006 prices.[179] The paper suggested parts of the existing Trident system be refitted to some extent to prolong their lives. However, the relatively short (five years) life extension potential of the Vanguard class meant that a new class of SSBNs should replace it in the 2020s. The first boat of the new SSBN class would take 17 years to be designed and built, making a five-year life extension of the Vanguard class necessary.[177]

A decision on the renewal of Trident was made on 4 December 2006. Prime Minister Tony Blair told MPs it would be "unwise and dangerous" for the UK to give up its nuclear weapons. He outlined plans to spend up to £20bn on a new generation of submarines for Trident missiles. He said submarine numbers may be cut from four to three, while the number of nuclear warheads would be cut by 20% to 160. Blair said although the Cold War had ended, the UK needed nuclear weapons, as no-one could be sure another nuclear threat would not emerge in the future.[180]

On 14 March 2007, the Labour government won House of Commons support for the plans to renew the submarine system. The proposals were passed by a majority of 248.[181][182] Despite a clarification that the vote was just for the concept stage of the new system, 95 Labour MPs rebelled, and it was only passed with the support of the opposition Conservative Party.[181][183] It was the first time MPs had been given the chance to vote on whether the UK should remain a nuclear power, and the biggest rebellion since the beginning of the 2003 Iraq War.[181] The Labour government proposed that the final decision to manufacture should be made in 2014.[184] The new 2010 coalition government agreed "that the renewal of Trident should be scrutinised to ensure value for money." Research and development work continued with an Initial Gate procurement decision, but the Main Gate decision to manufacture a replacement was rescheduled for 2016, after the 2015 general election.[note 2][184] The vote on whether to order the Successor-class was held on 18 July 2016 in the House of Commons; the motion passed with a significant majority,[186] extending the programme's life until at least the 2060s. Although 48 Labour MPs voted against it, 41 did not vote, and 140 Labour votes were cast in favour of the motion.[187]

Leanne Wood speaks at the #StopTrident rally on 27 February 2016. She was arrested on 8 January 2007 for protesting against the UK's Trident nuclear missile programme at Faslane.[188]

The 2010 Strategic Defence and Security Review concluded that the Successor-class submarines would have eight operational missiles carrying no more than 40 operational warheads between them. This would allow the UK to reduce its stocks of operational warheads from 160 to 120, and the overall stockpile from no more than 225 to no more than 180.[178] They would be carried in a 12-missile Common Missile Compartment designed in collaboration with the US which could accommodate the current Trident II D-5 missiles and any replacement missile once the D-5 reaches the end of its expected life in the 2040s.[178]

Two non-representative polls of experts from the RUSI and the Royal Institute of International Affairs (commonly known as Chatham House) were conducted in 2010. The RUSI found a majority for those who think the benefits of Trident outweigh the costs (53%) compared to those that think the costs outweigh the benefits (13%) or are evenly balanced (34%). The Chatham House poll found a minority in favour of Trident replacement (22%), with more in favour of replacing with a cheaper system (43%) and 29% saying the UK should not replace Trident at all.[189]

In April 2015, a YouGov poll found that 38% of people thought that Trident should be replaced in full, 28% wanted to replace it with a cheaper system, 19% thought the UK should completely give up its nuclear weapons, and 15% did not know.[190] In September 2015, a Survation poll found that 29% agreed that Trident should be reformed to make it cheaper, 26% that it should be renewed in full, and 18% that it should be scrapped. 27% did not know.[191] Nuclear weapons are not the nation's biggest issue, with just 2% of people saying that it was nation's biggest worry in May 2015, compared to 21% in June 1987.[192]

In February 2016, BAE Systems began design work on prototypes of the new submarines.[193] The Successor class was officially named the Dreadnought class on 21 October 2016.[194][176] The submarines were expected to become operational starting in 2028, with the current fleet phased out by 2032.[195][196]

In October 2015, Reuters estimated it would cost £167 billion over its 30-year lifespan, or £5.56 billion per year; this figure was disputed by Michael Fallon.[197] The Ministry of Defence put the cost of building, testing and commissioning the replacement vessels at £31 billion (plus a contingency fund of £10 billion) over 35 years. This amounts to 0.2 per cent of government spending, or 6 per cent of defence spending.[1] Crispin Blunt, Chair of the Foreign Affairs Select Committee, estimated in July 2016 that the programme would cost £179 billion in total over its lifetime.[198]

For the 2018/19 financial year the National Audit Office found that spending on the nuclear deterrent will cost £5.2 billion, or 14% of the defence budget, with £600 million of contingency funding used. Costs were projected at about £51 billion over the following 10 years, £2.9 billion above the projected budget which already anticipated finding £3 billion of savings, which the Daily Telegraph described as a £6 billion shortfall.[199][200]