• For the first time since the end of the Cold War, the UK plans to increase its nuclear warhead stockpile. The main principles of the UK’s nuclear policy have not changed, however. The focus is on deterring nuclear attack. The UK’s force will remain the minimum required for deterrence – though the definition of  ‘minimum’ may change in response to the evolving threat. The UK does not exclude the first use of nuclear weapons. And its nuclear weapons are designed to defend its NATO allies as well as itself.

• Not all the UK’s allies see its policy as credible. The UK needs to do a better job of explaining how its deterrent fits into the current security picture in Europe.
   

   

• Some of the countries that feel most threatened by Russia question the credibility of a nuclear guarantee from the UK, a country that commits few conventional forces to their defence – particularly as UK land forces are set to shrink further. Those countries look primarily to the US and its substantial conventional and nuclear forces in Europe for both defence and deterrence.

• In many parts of Western Europe, and especially in Germany, arms control is seen as more important than deterrence. Anything that highlights the role of nuclear weapons in NATO strategy, such as the UK’s announcement of an increase in its nuclear stockpile, is unwelcome in the eyes of governments under domestic pressure to do more for disarmament.

• Meanwhile, the Biden administration’s review of US nuclear posture has the UK and other allies nervous. Biden has in the past supported a change in policy to make clear that the sole purpose of US nuclear forces should be to deter and if necessary retaliate against a nuclear attack. Such a policy would imply that an adversary could launch a conventional attack without risking nuclear retaliation.

• Unlike the UK, France does not put its nuclear forces at the disposal of NATO or say explicitly that it would use them to defend its allies. Emmanuel Macron has, however, tried to convince other Europeans that France would show solidarity with them in a crisis, even if they had no role in decisions on the use of French nuclear weapons.

The UK should leverage its deterrent to strengthen security relations with its European partners:

• It should ensure that the current difficulties with France over Brexit issues do not contaminate its defence and security relationship with Paris, and recommit itself to bilateral nuclear co-operation. The two face similar questions over nuclear policy, and share similar concerns about where Biden might take US nuclear policy.

• It should make sure that the incoming German government understands the contribution the UK has made to nuclear arms control since 1991, as well as the reasoning behind the announced warhead increase.
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  It should ensure that Central European and Baltic allies believe in its commitment to use nuclear weapons to deter and if necessary defend them against attacks.