UN Secretary General Antonio Guterres called on Monday for a new global effort to get rid of nuclear weapons but said many states still wrongly think they make the world safer.
Officials and experts told Reuters earlier this month that Guterres was planning such an initiative, but a US official said at the time that nuclear disarmament was an "aspirational goal" only and warned against any bold initiative.
"There is great and justified anxiety around the world about the threat of nuclear war," Guterres told diplomats at the Conference on Disarmament, a long-stalemated forum at the United Nations complex in Geneva.
"Countries persist in clinging to the fallacious idea that nuclear arms make the world safer ... At the global level, we must work towards forging a new momentum on eliminating nuclear weapons," Guterres said.
He called for an urgent and wide-ranging arms control effort, not only for nuclear arms but also conventional and next generation weapons.
"We need to examine the potential risks and challenges posed by the weapons of the future. This includes the relationship between new technologies - autonomous and unmanned weapons, artificial intelligence, biotechnology and space-based systems - and international humanitarian and human rights law."
There are currently around 150,000 nuclear weapons worldwide and the arms trade is flourishing more than at any time since the Cold war, with $1.5 trillion of spending annually, he said.
Taboos on nuclear tests and chemical weapons usage were under threat, he added, while talk of tactical nuclear weapons was leading in an extremely dangerous direction.
"Each (poison) gas attack, each nuclear test, takes us into greater danger," Guterres said.
Earlier this month the United States published its "nuclear posture review", which justified an expansion of its "low-yield" nuclear capability by saying it would deter Russia's tactical nuclear weapons.
"The challenges are enormous, but history shows that it has been possible to reach agreement on disarmament and arms control even at the most difficult moments," Guterres said.
Last week diplomats and disarmament experts discussed Guterres's initiative with UN officials during a retreat near New York, and he is expected to launch his plans around April or May with "practical and implementable actions".
Richard Lennane, head of the non-profit Geneva Disarmament Platform, said it was encouraging and refreshing to see Guterres react to the parlous international security situation not by dismissing disarmament but by championing it.
"Whether or not his initiative will succeed, however, depends on the willingness of UN member states to cooperate."