At a Security Council session called by Japan, Guterres said that the biopic about the morally conflicted father of the atomic bomb "brought the harsh reality of nuclear doomsday to vivid life for millions around the world."

"Humanity cannot survive a sequel to Oppenheimer," Guterres said.

"We meet at a time when geopolitical tensions and mistrust have escalated the risk of nuclear warfare to its highest point in decades," he said.

Russian President Vladimir Putin has made thinly veiled threats to use nuclear weapons as he warns the West against its support for Ukraine, which Moscow invaded more than two years ago.

Without naming Putin, Guterres said, "Nuclear saber-rattling must stop."

"Threats to use nuclear weapons in any capacity are unacceptable," he said.

Elsewhere in the world, tensions surrounding nuclear-armed North Korea have continued to rise and Iran has been enriching uranium closer to the level needed if it decides to build an atom bomb.

Israel, the Middle East's only nuclear-armed power albeit an undeclared one, has been at war since an October 7 attack by Hamas militants.

Guterres called on the United States and Russia to resume negotiations, at a standstill since the Ukraine war, on a successor to the New START nuclear arms reduction treaty which expires in early 2026.

He also called for progress on other initiatives including the Treaty on the Prohibition of Nuclear Weapons, which entered into force in 2021 but has little practical effect as no nuclear-weapons states are party to it.