The United Kingdom's decision to boost its nuclear warhead stockpile would breach its obligations under the 1970 Nuclear Nonproliferation Treaty, U.N. Secretary-General António Guterres' spokesperson Stéphane Dujarric said on Wednesday.
Dujarric told a daily press briefing that the U.K.'s plans would violate the treaty's Article VI, which commits nations to "pursue negotiations in good faith on effective measures relating to cessation of the nuclear arms race at an early date and to nuclear disarmament, and on a treaty on general and complete disarmament under strict and effective international control."
The British government announced a day earlier that it aims to increase its nuclear stockpile so that it is prepared to defend itself and NATO allies.
"We do express our concern at the U.K.’s decision to increase its nuclear weapons arsenal, which is contrary to its obligations under Article VI of the NPT. It could have a damaging impact on global stability and efforts to pursue a world free of nuclear weapons," Dujarric told the briefing.
"At a time when nuclear weapon risks are higher than they have been since the Cold War," he said, "investments in disarmament and arms control is the best way to strengthen the stability and reduce nuclear danger."
That runs counter to British leaders' views. The British government said its new ambition is to increase its nuclear stockpile by 40% so that it can defend both itself and NATO allies.
Previously, the British government had planned to cut the U.K. stockpile of 195 warheads down to 180 this decade. But in its latest defense assessment, the government said that due to national security risks it now plans to increase the stockpile to 260 warheads.
"The U.K.’s independent nuclear deterrent has existed for over 60 years to deter the most extreme threats to our national security and way of life, helping to guarantee our security and that of our allies," the report said.
"We have previously identified risks to the U.K. from major nuclear armed states, emerging nuclear states, and state-sponsored nuclear terrorism," it said. "Those risks have not gone away. Some states are now significantly increasing and diversifying their nuclear arsenals."
The NPT requires signatory nations not to pursue nuclear weapons in exchange for a commitment by nuclear powers to progress towards nuclear disarmament. Nations that lack nuclear weapons are guaranteed access to peaceful nuclear technology for generating electricity.
The International Campaign to Abolish Nuclear Weapons, or ICAN, said the British government is now headed in the wrong direction.
“A decision by the United Kingdom to increase its stockpile of weapons of mass destruction in the middle of a pandemic is irresponsible, dangerous and violates international law," said ICAN’s Executive Director Beatrice Fihn.
"While the British people are struggling to cope with the pandemic, an economic crisis, violence against women, and racism, the government choses to increase insecurity and threats in the world," she said. "This is toxic masculinity on display.”