UN chief António Guterres has raised the alarm that the world is in most dangerous nuclear moment since the end of the cold war.

A statement by the UN on Tuesday highlighted Mr Guterres’ concern as the General Assembly held a high-level meeting to mark the International Day for the Total Elimination of Nuclear Weapons.

“We meet at the most dangerous nuclear moment since the end of the cold war,” Mr Guterres said, pointing to expanding and modernizing nuclear arsenals, louder nuclear sabre-rattling and increased odds of mistakes due to technological advances.

Expressing concern over the expiration of the New START (Strategic Arms Reduction Treaty) and failure of the eleventh Review Conference of the Treaty on the Non-Proliferation of Nuclear Weapons to reach consensus on a substantive outcome, the UN secretary-general said, “And just when they are most needed, the safeguards built over decades to contain these dangers are breaking down.”

Mr Guterres stated that “disarmament is not a favour” but “a binding legal obligation”, calling on nuclear weapon states to return to dialogue, reduce the role of nuclear weapons in their security policies and pursue confidence-building measures that ensure transparency.

Mr Guterres urged the United States and Russia to negotiate a successor framework to New START and stressed that it is “beyond time” to bring the Comprehensive Nuclear-Test-Ban Treaty into force, adding that “these devices of death must never decide the fate of humanity”.

Khalilur Rahman, UNGA president, also said the global stockpile was expected to grow again for the first time since the end of the cold war.

“New technologies—including artificial intelligence, cyber-capabilities and advanced delivery systems—are introducing additional uncertainty into command, control and decision-making,” Mr Rahman said.

Noting that the combination of proliferating conflicts, eroding arms-control arrangements and renewed reliance on nuclear weapons creates a perilous moment for international peace and security, Mr Rahman said, “We must change course, urgently and decisively.”