COVID-19 and British Nuclear Deterrence

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In early April, British Prime Minister Boris Johnson nearly died. Suffering from COVID-19, Johnson spent three nights in the intensive care unit before eventually recovering and being discharged. Without the expert and round-the-clock attention of his medical team, the prime minister later admitted, he may not have survived.

Johnson’s stint in an intensive care unit raised a sensitive question related to British national security — with the prime minister incapacitated, who was authorized, if required, to launch the country’s nuclear weapons?

For fifty years, Britain has conducted continuous at sea deterrent patrols. Through these patrols — entitled Operation Relentless — the Royal Navy has persistently maintained at least one of its four ballistic missile submarines in the world’s oceans to guarantee that its nuclear arsenal is prepared for use at any time. The uninterrupted deployment of ballistic missile submarines is a central pillar of Britain’s nuclear planning and currently serves as the backbone of the United Kingdom’s strategic nuclear deterrent.



Even if only temporarily, the prime minister’s recent health crisis produced ambiguities in the nuclear chain of command and could have rendered Britain’s nuclear forces inert. Conservative member of parliament and Chair of the House of Commons Defence Select Committee Tobias Ellwood voiced this concern, observing that “it is important to have 100 percent clarity as to where responsibility for U.K. national security decisions now lies.”

Statements by political leaders, however, offered little guidance on how the United Kingdom adjusted its nuclear chain of command, if at all. Foreign Secretary and First Secretary of State Dominic Raab agreed to deputize “where necessary” while the prime minister recovered, but it remains unclear whether he possessed the power to order nuclear use. When asked by the BBC whether Raab had inherited the authority to use nuclear weapons, Cabinet Office minister Michael Gove demurred, simply replying that he “cannot talk about national security issues.”

COVID-19 has certainly disrupted and raised questions about Britain’s routine nuclear command and control procedures. However, it’s unlikely that the pandemic could lead to crippling command failures, such as precluding political leaders from transmitting nuclear use orders to military operators or preventing military forces from receiving and conducting an authorized nuclear attack. British nuclear command and control systems are designed to function even if all political leaders with formal nuclear launch authority are incapacitated. The ability to conduct nuclear operations under such circumstances reflects the United Kingdom’s emphasis on robust command and control systems that originated during the Cold War and have persisted to contemporary nuclear planning.

Instead, the primary threat that COVID-19 poses to British arsenal readiness is its potential to directly impact military operators. Whereas the upper levels of the nuclear chain of command are robust and reliable, Britain’s exclusive reliance on a single, at sea ballistic missile submarine to maintain strategic deterrence makes the United Kingdom’s nuclear arsenal vulnerable to disruptions if COVID-19 directly impacts crewmembers of Britain’s ballistic missile submarines or the personnel responsible for repairs and maintenance of those submarines. COVID-19 therefore poses challenges to British policymakers as they seek to maintain continuous at sea deterrent patrols and rotate crews and vessels on schedule. If COVID-19 cripples the nuclear ranks of the Royal Navy, policymakers may face a world in which the United Kingdom has no operationally deployed nuclear weapons available to maintain its strategic nuclear deterrent.

Nuclear Decapitation by COVID-19?

Nuclear weapons serve several purposes for British foreign policy, including the promotion of greater national independence — both from its adversaries and its allies — and robust deterrence against nuclear aggression. Britain’s strategic nuclear doctrine views nuclear weapons as a “deterrent of last resort” and asserts that nuclear weapons “would only be used in extreme circumstances of self-defense.” The British nuclear deterrent therefore hinges upon the credibility of its threat to respond to aggression with nuclear weapons under any circumstances.

Public concerns regarding the impact of COVID-19 on Britain’s nuclear command and control systems — referring to the operational means by which a state conducts the management, deployment, and potential release of nuclear weapons — capture a fundamental challenge of nuclear deterrence. In order to credibly deter an adversary, decision-makers must be able to authorize and communicate orders to use nuclear weapons under any circumstances. If COVID-19 renders political leaders unable to authorize nuclear use because these individuals are incapacitated or the procedures for devolution of nuclear launch authority become unclear, the United Kingdom’s ability to use nuclear weapons might falter. Such a disconnect between political leaders with the authority to order nuclear use and military operators in possession of nuclear assets would fundamentally undermine deterrence and create a window of vulnerability that adversaries — especially Russia — could exploit. COVID-19 therefore threatens to create a gap in the United Kingdom’s strategic nuclear deterrent for the first time in the era of continuous at sea deterrent patrols. Domestically, the costs of maintaining continuous at sea deterrent patrols has also renewed longstanding debates in Britain about the utility of nuclear weapons, as critics suggest that investments in nuclear weapons should instead be redirected to support public health programs and offset the economic costs of COVID-19.

Since 1969, ballistic missile submarines have constituted the United Kingdom’s primary strategic nuclear delivery platform. The Royal Navy presently operates four Vanguard-class submarines carrying Trident II D5 ballistic missiles. Under normal circumstances, one submarine is deployed at sea and conducting a deterrent patrol, two submarines remain in port and prepared to deploy in the event of a crisis, and the fourth submarine is undergoing extensive maintenance that precludes deployment. Given that ballistic missile submarines are difficult to track and target, British policymakers rely on this delivery platform to serve as a reliable cornerstone of the United Kingdom’s nuclear deterrent.

Mobility and concealment make ballistic missile submarines highly survivable, but the prospect of nuclear decapitation — an attack that disrupts the target’s command and control systems and makes it impossible to coordinate retaliatory strikes — could potentially undermine Britain’s nuclear deterrent. To guarantee that nuclear weapons are always prepared for use, the United Kingdom has adopted “delegative” command and control systems that provide peripheral military commanders with the ability to use nuclear weapons at all times. These delegative control systems provide Britain’s military operators with physical control of nuclear warheads and delivery systems, forego technical barriers to nuclear use, and enable the military to use nuclear weapons without necessarily requiring political authorization. By delegating the ability to use nuclear weapons to military commanders during peacetime, Britain significantly reduces the likelihood of an adversary conducting a successful nuclear decapitation strike. This posture allows command and control systems to “fail deadly,” meaning that if communications between political leaders and military operators are severed, the military still has the ability to use nuclear weapons unilaterally. These command and control arrangements protect against decapitation but, by providing military operators with the physical, technical, and administrative means for nuclear use, also increase the likelihood of unauthorized use. Nevertheless, British policymakers accept this risk and continue to rely on military professionalism as the primary safeguard against unauthorized use.

The specific arrangements of British nuclear command and control demonstrate the resilience of these systems to nuclear decapitation. Physically, the Royal Navy possesses all necessary components to launch nuclear weapons on board its ballistic missile submarines when conducting deterrent patrols. Technically, the United Kingdom has purposefully avoided implementing nuclear-use controls that would impede the ability of the military to use nuclear weapons in a crisis setting when communications between political leadership and ballistic missile submarines might be severed. Administratively, although the United Kingdom’s 2015 National Security Strategy and Strategic Defence and Security Review states that “only the Prime Minister can authorize the use of nuclear weapons,” the Royal Navy’s ballistic missile submarine crews always have the ability to use nuclear weapons, even if not the authority.

Two administrative controls protect British nuclear command and control systems from decapitation. First, since 2001 the United Kingdom has reinstated a Cold War policy that allows the prime minister to appoint up to three deputies who have the authority to commit nuclear forces in the event of the prime minister’s death or incapacitation. Second, upon assuming office each prime minister writes a “letter of last resort” that remains in a safe aboard Britain’s ballistic missile submarines. This letter provides instructions to the submarine’s commander on how to proceed in the event that the submarine cannot communicate with political leadership during a crisis and guarantees that all ballistic missile submarines sail “with all the information onboard necessary to conduct a strategic missile launch.” If a submarine loses communications with British policymakers, the crew attempts to listen to the BBC Radio 4 Today show. If the show cannot be heard, the submarine crew is to assume that the United Kingdom has been attacked and should then access the letter of last resort to perform a politically designed task, such as placing the submarine under U.S. command, sailing to Australia, targeting the state responsible for attacking the United Kingdom, or deferring to the judgment of the submarine’s commander.

These measures suggest that COVID-19 is very unlikely to undermine Britain’s nuclear deterrent by disrupting political control over nuclear use authority. During the Cold War, British policymakers developed the country’s nuclear command and control systems to function in the aftermath of a nuclear attack on Britain’s political leadership. The same emphasis on maintaining operational viability remains prominent in post-Cold War British nuclear thinking.

If anything, the United Kingdom’s nuclear command and control systems are overprepared for any threat of nuclear decapitation posed by COVID-19. British command and control systems are designed to withstand attacks that happen quickly and on a massive scale. For example, by the early 1960s analysts estimated that the warning time for a Soviet missile attack on the United Kingdom was approximately four minutes. Such an attack could eliminate all senior political figures and would likely destroy the necessary infrastructure for any surviving decision-makers to communicate with a deployed ballistic missile submarine.

In comparison to a massive nuclear attack on Britain’s command and control systems, COVID-19 is vastly less threatening to the operational readiness of the British nuclear arsenal. Whereas a nuclear attack on Britain’s political leadership and command and control infrastructure could almost instantly incapacitate the entire political chain of command, COVID-19 would apply pressure to political leaders over a period of days or weeks. Indeed, the orderly transfer of governing authority from Johnson to Raab was made possible by a generous timeframe. Although British officials have historically declined to specify which individuals serve as deputies with nuclear launch authorization on grounds of national security, these procedures seemingly support the devolution process identified by Jeffrey Lewis and Bruno Tertrais, in which the prime minister can appoint deputies to manage nuclear decisions in case the prime minister is incapacitated at some point in the future. Furthermore, even if COVID-19 incapacitates all political leaders in the nuclear chain of command at once, the persistent delegation of nuclear use capability to the Royal Navy’s ballistic missile submarines guarantees that nuclear weapons can be used in the event of a crisis without requiring political authorization. Combined, these measures suggest that the United Kingdom’s nuclear deterrent remains credible and resilient to the pressures that COVID-19 places on the nuclear chain of command.

COVID-19 and the Threat to Operational Nuclear Readiness

The primary danger that COVID-19 poses to the United Kingdom’s strategic nuclear deterrent is its potential effects on military operators in the Royal Navy’s nuclear-armed submarines. An outbreak of COVID-19 on Britain’s ballistic missile submarines could ultimately force policymakers to choose between maintaining continuous at sea deterrent patrols to preserve credible deterrence or accepting a temporary stoppage of deterrent patrols to protect servicemembers.

COVID-19 is already affecting military readiness in multiple countries as leaders restrict movements and reduce military exercises. To date, the U.S. Navy alone has identified COVID-19 cases on four of its aircraft carriers. The outbreak of COVID-19 on the USS Theodore Roosevelt — with over 700 positive cases as of April 21 — provides a vivid example of the challenges facing military commanders as the pandemic continues to spread, with Capt. Brett Crozier writing a letter that outlined his concerns about the dangers of a COVID-19 outbreak on the ship before being fired by then-Acting Secretary of the Navy Thomas Modly. Elsewhere, Russia placed the entire crew of its K-266 Orel submarine under quarantine after identifying a positive case of coronavirus onboard the vessel. The Netherlands also terminated an ongoing exercise after the HNLMS Dolfijn identified eight positive cases of COVID-19. France has confirmed COVID-19 in nearly 60 percent of sailors on its flagship aircraft carrier, the Charles de Gaulle. In each of these cases, COVID-19 has significantly impacted the warfighting readiness of military forces.

The United Kingdom’s reliance on ballistic missile submarines as the only operational leg of its nuclear arsenal makes its nuclear deterrent particularly vulnerable to disruptions by COVID-19. With approximately 130 servicemembers confined in extremely close quarters, the United Kingdom’s Vanguard-class submarines provide extremely favorable conditions for the virus to spread. The lack of an air- or land-based nuclear delivery platform, however, means that ballistic missile submarines must remain in service to prevent a gap in the operational readiness of Britain’s nuclear forces. If the military personnel of the ballistic missile submarine fleet are unable to conduct continuous at sea deterrent patrols, Britain’s nuclear arsenal will lack the operational capability to deter potential adversaries.

That the Royal Navy only operates four Vanguard-class submarines further exacerbates the challenges posed by COVID-19 for maintaining continuous at sea deterrent patrols. Three specific challenges arise. First, with only one deployed submarine conducting deterrent patrols, COVID-19 can have a direct and immediate impact on the readiness of Britain’s nuclear forces. If the deployed submarine experiences an outbreak of COVID-19 cases, it will be difficult to contain the spread of the virus onboard the submarine. The spread of COVID-19 would likely affect a large portion of crewmembers, including key individuals involved in the nuclear launch process.

Second, if a severe spread of COVID-19 forces a deployed ballistic missile submarine to return early from its deterrent patrol, the submarine designated to replace the returning vessel could face similar problems. If the crewmembers of the second ballistic missile submarine are not isolated and quarantined in advance of their patrol to confirm that they are completely free of COVID-19, the second submarine could deploy with individuals carrying COVID-19 and experience another outbreak within the fleet of ballistic missile submarines. In this scenario, the United Kingdom nuclear arsenal would be reduced to one remaining ballistic missile submarine prepared for deployment and two ballistic missile submarines with widespread cases of COVID-19 that might preclude their deployment. Such a beleaguered nuclear force would have questionable reliability and would possess no viable alternatives for independently generating nuclear deterrence.

Third, COVID-19 threatens to interfere with the routine maintenance procedures that allow the Royal Navy to rotate ballistic missile submarines on schedule. If COVID-19 reaches the crewmembers responsible for the storage, processing, and maintenance of nuclear-armed submarines at HM Naval Base Clyde in Scotland — commonly referred to as Faslane — the Royal Navy will face further pressures on key personnel responsible for ensuring military readiness. These crews are already facing greater demand for their services than usual, as recent reports revealed that two of Britain’s four Vanguard-class submarines have been under repair for the past year, rather than the typical rotation of one submarine under maintenance at a time. With only two ballistic missile submarines currently capable of operational deployment, the United Kingdom’s nuclear deterrent has very little remaining room for error.

While the Royal Navy confronts reduced availability of operationally viable ballistic missile submarines and threat of COVID-19 to its operators and crewmembers, the Russian Navy has conducted “unusually high” levels of activity in the North Sea and the English Channel. British policymakers expressed concern that Russia conducted these operations to test the United Kingdom’s defenses during the pandemic. With more than 10,000 members of Britain’s armed forces serving in support of domestic efforts to provide logistical support and supplies to the National Health Service, the United Kingdom’s conventional forces are also spread thin. Although the Royal Navy was able to effectively mobilize and respond by deploying nine ships to shadow seven Russian vessels during this episode, Russia’s naval activities demonstrate how any increase in external pressure on the United Kingdom’s security can place additional strain on British military forces that are already facing strains imposed by COVID-19.


COVID-19 will not undermine British nuclear deterrence by incapacitating the prime minister or his deputies. Long-standing and institutionalized procedures allow for the devolution of nuclear command authority to other political leaders, and the military custodians of nuclear assets retain the ability to launch nuclear weapons at all times.

Instead, the greater threat to Britain’s nuclear deterrent is the potential for COVID-19 to directly affect crewmembers onboard nuclear-armed ballistic missile submarines and the personnel responsible for the maintenance and repair of these vessels. If the crews for either the patrolling or reserve vessels experience an outbreak of COVID-19, Britain may not be able to maintain continuous at sea deterrent patrols for the first time in over fifty years. This could tempt Russia to take advantage of a temporary moment of weakness, undermine the credibility and sustainability of Britain’s nuclear posture, and damage the country’s reputation as a leading military power.

The most important measures for sustaining Britain’s nuclear deterrent will emphasize the health of the Royal Navy’s ballistic missile submarine crewmembers. The Ministry of Defence’s decision to quarantine crewmembers for two weeks before deployment represents a critical, proactive step toward ensuring that the rotation of ballistic missile submarines will operate on schedule. Each Vanguard-class submarine has two captains and two crews — known as “Port” and “Starboard” — that allow one crew to patrol aboard the submarine while the other crew trains and takes leave. By canceling the rest and recuperation period for all personnel associated with forthcoming deployments, British leaders have developed necessary contingency plans to provide redundancy.

Although Johnson’s recent health crisis and the potential effects it had on the United Kingdom’s nuclear deterrent have received greater attention in the public sphere, the country’s nuclear command and control systems are capable of handling those disruptions. The challenge of guaranteeing that COVID-19 does not affect the military personnel that conduct continuous at sea deterrent patrols represents the more important task for maintaining British nuclear deterrence. If COVID-19 reaches the submarine crewmembers conducting deterrent patrols or the personnel that keep continuous at sea deterrent patrols on schedule, this is the most likely pathway through which the United Kingdom experiences a gap in its strategic nuclear deterrent.



David Arceneaux is a postdoctoral fellow at Harvard University’s Belfer Center for Science and International Affairs, affiliated with the International Security Program and the Project on Managing the Atom. David’s research focuses on nuclear strategy and operations, including an ongoing book project on the origins of command and control systems in regional nuclear powers.

Image: Flickr (Image by Robert Sullivan)