The United Nations chief warned that "humanity is just one misunderstanding, one miscalculation away from nuclear annihilation," citing the war in Ukraine, nuclear threats in Asia and the Middle East and many other factors.
Secretary-General Antonio Guterres gave the dire warning at the opening of the long-delayed high-level meeting to review the landmark 50-year-old treaty aimed at preventing the spread of nuclear weapons and eventually achieving a nuclear-free world.
The danger of increasing nuclear threats and a nuclear catastrophe was also raised by the United States, Japan, Germany, the UN nuclear chief and many other opening speakers at the meeting to review progress and agree on future steps to implement the Nuclear Nonproliferation Treaty, known as the NPT.
US Secretary of State Antony Blinken said North Korea is preparing to conduct its seventh nuclear test, Iran "has either been unwilling or unable" to accept a deal to return to the 2015 nuclear agreement aimed at reining in its nuclear program, and Russia is "engaged in reckless, dangerous nuclear sabre-rattling" in Ukraine.
He cited Russian President Vladimir Putin's warning after its Feb. 24 invasion that any attempt to interfere would lead to "consequences you have never seen", emphasising that his country is "one of the most potent nuclear powers".
This is contrary to assurances given to Ukraine of its sovereignty and independence when it gave up its Soviet-era nuclear weapons in 1994, Blinken said and sends "the worst possible message" to any country thinking it needs nuclear weapons to defend itself and deter aggression.
Japanese Prime Minister Fumio Kishida said divisions in the world since the last review conference in 2015, which ended without a consensus document, have become greater, stressing that Russia's threat to use nuclear weapons in the Ukraine war has contributed "to worldwide concern that yet another catastrophe by nuclear weapon use is a real possibility".
German Foreign Minister Annalena Baerbock accused Russia of "brutally violating the assurances" it gave Ukraine in 1994 and said Moscow's "reckless nuclear rhetoric" since its invasion of its smaller neighbour "is putting at risk everything the NPT has achieved in five decades".
Putin appeared to roll back on his nuclear warning in a message of greetings to NPT participants posted on his website.
"We believe that a nuclear war cannot be won and must never be fought, and we stand for equal and indivisible security for all members of the world community," the Russian leader said.
Putin said his country "consistently follows the letter and spirit" of the NPT and expects all parties to "strictly comply with their commitments" and make "a significant contribution" at the conference to strengthen the non-proliferation regime "to ensure peace, security and stability in the world".
Most recently, Blinken said Russia seized Europe's largest nuclear power plant in Zaporizhzhya and is using it as a military base to fire at Ukrainians, "knowing that they can't and won't shoot back because they might accidentally strike a nuclear reactor or highly radioactive waste in storage". He said this brings the notion of having "a human shield to an entirely different and horrific level".
Rafael Grossi, director general of the International Atomic Energy Agency, said the Ukraine conflict is "so grave that the spectre of a potential nuclear confrontation, or accident, has raised its terrifying head again".
He warned that at the Zaporizhzhya nuclear plant "the situation is becoming more perilous by the day," and he urged all countries to help make possible his visit to the plant with a team of IAEA safety and security experts, saying his efforts for the past two months have been unsuccessful.
Guterres told many ministers, officials and diplomats gathered in the General Assembly Hall that the month-long review conference is taking place "at a time of nuclear danger not seen since the height of the Cold War".
The conference is "an opportunity to hammer out the measures that will help avoid certain disasters, and to put humanity on a new path towards a world free of nuclear weapons", the secretary-general said.
But Guterres warned that "geopolitical weapons are reaching new highs," almost 13,000 nuclear weapons are in arsenals around the world, and countries seeking "false security" are spending hundreds of billions of dollars on "doomsday weapons".
"All this at a time when the risks of proliferation are growing and guardrails to prevent escalation are weakening," he said, "And when crises - with nuclear undertones -- are festering from the Middle East and the Korean Peninsula to the invasion of Ukraine by Russia, and to many other factors around the world."
Guterres called on conference participants to take several actions: urgently reinforce and reaffirm "the 77-year-old norm against the use of nuclear weapons," work relentlessly toward eliminating nuclear weapons with new commitments to reduce arsenals, address "the simmering tensions in the Middle East and Asia" and promote the peaceful use of nuclear technology.
"Future generations are counting on your commitment to step back from the abyss," he implored the ministers and diplomats. "This is our moment to meet this fundamental test and lift the cloud of nuclear annihilation once and for all."
Japan's Kishida, recalling his home city of Hiroshima where the first atomic bomb was dropped in August 1945, echoed many of Guterres' points saying the path to a world without nuclear weapons has become harder but "giving up is not an option".
In force since 1970, the Nonproliferation Treaty known as the NPT has the widest adherence of any arms control agreement, with some 191 countries that are members.
Under its provisions, the five original nuclear powers - the United States, China, Russia (then the Soviet Union), Britain and France - agreed to negotiate toward eliminating their arsenals someday and nations without nuclear weapons promised not to acquire them in exchange for a guarantee to be able to develop nuclear energy for peaceful purposes.
India and Pakistan, which didn't join the NPT, went on to get the bomb. So did North Korea, which ratified the pact but later announced it was withdrawing. Non-signatory Israel is believed to have a nuclear arsenal but neither confirms nor denies it. Nonetheless, the treaty has been credited with limiting the number of nuclear newcomers (U.S. President John F. Kennedy once foresaw as many as 20 nuclear-armed nations) as a framework for international cooperation on disarmament.
The meeting, which ends August 26, aims to generate a consensus on the next steps, but expectations are low for a substantial — if any — agreement. There were 133 speakers as of Monday, plus dozens of side events.
The NPT's five-year review was supposed to take place in 2020, when the world already faced plenty of crises, but was delayed because of the Covid-19 pandemic.
Patricia Lewis, former director of the U.N. Institute for Disarmament Research who is now in charge of international security programs at the international affairs think tank Chatham House in London, said "President Putin's threats to use nuclear weapons have shocked the international community."
Russia is not only an NPT signatory but a depository for treaty ratifications and in January it joined the four other nuclear powers in reiterating the statement by former U.S. President Ronald Reagan and former Soviet leader Mikhail Gorbachev that "a nuclear war can never be won and must never be fought", she told AP.
Lewis said countries participating in the review conference will have a difficult decision to make.
To support the treaty and what it stands for, "governments will have to address Russia's behaviour and threats", she said. "On the other hand, to do so risks dividing the treaty members - some of whom have been persuaded by Russia's propaganda or at least are not as concerned, for example, as the Nato states."
And "Russia no doubt will strenuously object to being named in statements and any outcome documents".
The site was used by Hezbollah to plan attacks on Israeli civilians.