The UK Government intends to increase the number of warheads available to its nuclear fleet at Faslane from 180 to a maximum of 260 as part of its integrated review of defence and foreign policy.
A document prepared as part of the review claims the cap will be raised “in recognition of the evolving security environment”, but the move has been widely questioned.
Now academics at the London School of Economics (LSE) have warned the increase in warheads would be inconsistent with the Treaty on the Non-Proliferation of Nuclear Weapons, to which the UK is a nuclear weapon state party.
Christine Chinkin, emerita professor of international law at LSE, and Dr Louise Arimatsu, a distinguished policy fellow at the institution’s Centre for Women, Peace and Security, said the increase constitutes a breach of article six of the treaty.
The academics were commissioned to examine the legal implications of the raised cap, which bucks a decades-long trend of gradual disarmament, by the Campaign for Nuclear Disarmament (CND).
Kate Hudson, the CND’s general secretary, told the Daily Record: "The increase in the UK’s nuclear arsenal has been exposed to intense criticism nationally and internationally, including from the United Nations.
"Thanks to the work of highly respected academic experts, we now know it is illegal under international law.
"Everything points to the decision costing tens of billions of pounds. During this pandemic, there are other urgent uses for public money.”
She added: "The decision breaks with the gradual nuclear reductions implemented by successive governments going back nearly 30 years and is at odds with the decision by Presidents [Joe] Biden and [Vladimir] Putin to continue bilateral nuclear reductions."
Stewart McDonald MP, the SNP’s shadow defence spokesman, said the move to bolster Britain’s nuclear stockpile was an “obscene waste of money” in the midst of a pandemic, as well as being “completely at odds” with the treaty.
"For Boris Johnson to previously champion the idea of international rule-based systems before announcing in the same breath that his government plans to violate its commitments to the international treaty of non-proliferation is truly staggering,” he said.
“It is clear that the UK Government has no intention of removing weapons of mass destruction from Scotland – and Westminster’s single-minded nuclear weapons obsession, and the amount of money wasted on it, highlights the democratic deficit we currently face.”
He added the only way to ensure Faslane became a conventional defence base was by delivering independence for Scotland.
A Ministry of Defence spokeswoman said: “Maintaining the UK’s nuclear deterrent capability at a minimum credible level is fully consistent with our international legal obligations, including those under article six of the Non-Proliferation Treaty.
"The UK’s independent nuclear deterrent exists to deter the most extreme threats to the UK and our NATO allies. Our stockpile ceiling is a maximum if required, not a target nor our current number, and is kept under review.”