United Kingdom: Prof. Malcolm Chalmers and Tom Plant

Nuclear deterrence is seen as being the cornerstone of UK and European security. The UK’s own nuclear deterrent is central to this, dedicated to NATO but also the ultimate guarantor of national security. NATO's role as a nuclear alliance is central to its ability to deter nuclear-armed adversaries, most of all (at present) Russia. The government is comfortable with both of these, and would strongly oppose any suggestion that NATO should no longer be a nuclear alliance.

This is not a matter to which senior policy makers give much thought. Insofar as some thought is given, the DCA capability is seen to be a primarily symbolic one, reassuring the US that the DCA states are committed to nuclear deterrence. There are no doubt nuclear planners who worry about capability gaps in some scenarios were dual-key DCA no longer available in Germany. There is probably some interest at technical levels on whether new low-yield US SLBM (submarine-launched ballistic missile) warheads replace DCA B61 capabilities, and/or whether future air-based nuclear capabilities need to be missile-launched to be credible, given Russian air defenses. But the primary lens through which this is viewed is symbolic. The question is not about why Germany and DCA, therefore, but about why not. There is a bias in favor of the status quo.

The likely UK reaction would firstly be to try to understand why Germany wanted to do this, and in particular whether it was part of a wider rejection of nuclear deterrence. If it was, this would be very serious and would lead to escalation of the engagement to a very senior level. Assuming it was not, the UK would likely want to help to find ways that Germany could reassure its allies – especially the US but also the UK – that it was taking other steps to provide this reassurance, and in the meantime get reassurance that the process would take some time to carry out. These measures could include more US DCA deployments into Germany and/or more German conventional spending or commitments, and/or German commitment to supporting the DCA of other allies. Provided Germany made it clear that it wanted to reassure, the UK instinct would be to try to avoid this becoming a threat to Alliance cohesion, and try to kick the issue into the long grass in a NATO committee. It would not want to encourage the US to generate a big public row, although probably would not able to do much to stop this under this administration.