UN chief warns 'nuclear shadow' has returned to haunt humanity

The shadow of nuclear apocalypse, which loomed over humanity last century, has made a comeback, UN Secretary-General Antonio Guterres said.

"Geopolitical divides, relentless arms competition  have created a total deadlock," he said at the Conference on Disarmament. "Militaries are developing terrifying new applications of new and emerging technologies - including artificial intelligence and autonomous weapons systems."

"The nuclear shadow that loomed over humanity last century has returned," he went on to say.

"Some statesmen regularly imply that they are fully prepared to unleash nuclear hell - an outrageous threat that the world must condemn with clarity and force," the UN chief continued.