Under British nuclear doctrine, the United Kingdom would only consider firing a nuclear weapon in self-defense—a policy that would not appear to include Ukraine.
Russia’s invasion of Ukraine more than three years ago brought the specter of nuclear conflict back to the forefront. At various points during the bloody conflict, Russian officials have threatened a nuclear strike in Ukraine or against NATO.
America Was Genuinely Worried About Nuclear Use in 2022
Though the nuclear threats by Russian leader Vladimir Putin and others in his inner circle—notably former Russian president and current deputy chairman of the Russian national security council Dmitry Medvedev—have typically been dismissed in the West as empty saber-rattling, some high-level officials have worried about the content of those threats. Former CIA director, Bill Burns even revealed that the US government believed there had been a “genuine risk” of a Russian tactical nuclear strike in the fall of 2022, during Ukraine’s successful counteroffensive in the north.
“There was a moment in the fall of 2022 when I think there was a genuine risk of a potential use of tactical nuclear weapons,” the former CIA leader stated. Others observed that Russia likely believed a tactical nuclear strike in Ukraine would not lead to a broader nuclear war with the West, an unthinkable outcome on either side.
Russian President Vladimir Putin believed that he was entering into a quick conflict that would last anywhere between three days and two weeks. Not only could his forces not achieve their goals, but the Ukrainian forces also counterattacked, liberating hundreds of square miles of territory in just a few days. It was at that point that the Kremlin contemplated a tactical nuclear strike to reverse the situation on the battlefield.
Fortunately for global security, that delicate moment passed—but the threat has remained. The incident alarmed NATO member states, particularly the United Kingdom.
Understanding Britain’s Nuclear Doctrine
In June, the British Ministry of Defence released its 2025 Strategic Defence Review. The document offers insight into how the closest and most important US ally perceives the global security situation. The Strategic Defence Review also outlines London’s nuclear doctrine.
Under British nuclear doctrine, the United Kingdom would only consider firing a nuclear weapon in self-defense, including defending NATO allies. This would not appear to include Ukraine, which is not a member of NATO.
“The foundation of the UK’s approach to deterrence remains a minimum, credible, independent UK nuclear deterrent, assigned to the defence of NATO,” the British Ministry of Defence states in its latest Strategic Defence Review. “The purpose of the UK’s nuclear weapons is to preserve peace, prevent coercion, and deter aggression.”
The UK is one of the first nuclear powers in the world, achieving a nuclear weapons capability in 1952 after the United States and the Soviet Union. Today, Britain has approximately 225 nuclear warheads, 120 of which are deployed and 105 stored in reserve. The British military mainly relies on four Vanguard ballistic missile submarines carrying Trident II D5 ballistic nuclear missiles. For security purposes, at least one of Britain’s nuclear-equipped submarines is always on patrol, guaranteeing the country a second-strike capability.
According to British nuclear doctrine, only the incumbent prime minister can authorize the use of nuclear weapons, thus ensuring that the government maintains constant control of the deadly weapons. Interestingly, however, an outgoing prime minister can also dictate the use of nuclear munitions in certain circumstances. Every time a Royal Navy submarine embarks on a Continuous-At-Sea-Deterrent mission, the captain receives a sealed letter from the prime minister with instructions on how to use nuclear weapons in the event of a nuclear conflict. So, one could envision a scenario—albeit a disastrous one—where a Royal Navy submarine launches a nuclear ballistic missile based on the instructions of a former prime minister because the sitting government has been annihilated by a nuclear strike.
About the Author: Stavros Atlamazoglou
Stavros Atlamazoglou is a seasoned defense journalist specializing in special operations and a Hellenic Army veteran (national service with the 575th Marine Battalion and Army HQ). He holds a BA from the Johns Hopkins University and an MA from the Johns Hopkins’ School of Advanced International Studies (SAIS). His work has been featured in Business Insider, Sandboxx, and SOFREP.
Image: Shutterstock / richardjohnson.
