Antonio Guterres, UN secretary-general, says the fears of nuclear war are still with humanity, 73 years since the Hiroshima and Nagasaki nuclear bombs in August 1945.
Guterres said countries still spent large sums of money on arms and armies.
The UN chief said: “Sadly, 73 years on, fears of nuclear war are still with us.
“Millions of people, including here in Japan, live in a shadow cast by the dread of unthinkable carnage.
“States in possession of nuclear weapons are spending vast sums to modernise their arsenals.
“More than $1.7 trillion dollars was spent in 2017 on arms and armies – the highest level since the end of the Cold War and around 80 times the amount needed for global humanitarian aid.”
Guterres said disarmament processes have slowed, and even come to a halt, and many states demonstrated their frustration by adopting the Treaty on the Prohibition of Nuclear Weapons in 2017.
“Let us also recognise the persistent peril of other deadly weapons,” he said.
“Chemical and biological weapons of mass destruction, and those being developed for cyberwarfare pose a grave threat.
“Conflicts fought with conventional weapons are lasting longer and are becoming more deadly for civilians.
“There is an urgent need for disarmament of all kinds, but especially nuclear disarmament.”
The secretary-general said the consequences of nuclear weapons was the backdrop of the global disarmament initiative that he launched in May.
He said disarmament was a driving force for maintaining international peace and security.
Guterres added that it was a tool for ensuring national security and helps to uphold the principles of humanity, promote sustainable development and protect civilians.
He said his agenda for disarmament was based on concrete measures that would lower the risk of nuclear annihilation, prevent conflict of all kinds and reduce the suffering that the proliferation and use of arms cause to civilians.
The UN chief said the agenda made clear that nuclear weapons undermined global, national and human security.
He added that total elimination of nuclear weapons remained the highest disarmament priority of the United Nations.
Guterres conveyed deepest respect and condolences to all the victims and survivors of the atomic bombs that killed and injured tens of thousands of people in the immediate aftermath of the blasts.
He said the survivors of Nagasaki and Hiroshima – the Hibakusha – have become leaders for peace and disarmament in Japan and around the world.
He added: “Here in Nagasaki, I call on all countries to commit to nuclear disarmament and to start making visible progress as a matter of urgency.
“Let Nagasaki and Hiroshima remind us to put peace first every day; to work on conflict prevention and resolution, reconciliation and dialogue and to tackle the roots of conflict and violence.”
He said peace is not an abstract concept and it does not come about by chance but is tangible and can be built by hard work, solidarity, compassion and respect.