United Nations Secretary-General António Guterres warned Monday that the world was "one uncalculated step" that could lead to "nuclear annihilation" as it faces a threat "unmatched since the height of the Cold War".

"We have been exceptionally lucky so far. But luck is not a strategy and does not protect against geopolitical tensions that escalate to the point of a nuclear conflict," Guterres said at the start of a conference of the signatories to the Treaty on the Non-Proliferation of Nuclear Weapons.

The Secretary-General warned of the increasing dangers of nuclear proliferation against the backdrop of the crises in the Middle East and the Korean peninsula, and the Russian-Ukrainian war.

He added: There are now about 13,000 nuclear weapons in military arsenals around the world.

He stressed that the world needs the Treaty on the Non-Proliferation of Nuclear Weapons now more than ever.

There is no winner in nuclear war

For his part, Russian President Vladimir Putin stressed on Monday that there can be no "winners" in a nuclear war that should "never be unleashed."

In a speech he delivered during the Tenth Conference on the Non-Proliferation of Nuclear Weapons, which opened at the United Nations Headquarters in New York, he stressed that Russia remained faithful to the "text and spirit" of the treaty.

"There can be no winners in a nuclear war, and it should never be unleashed," he said.

Over the past months, Russia has threatened to use its nuclear weapons if it feels a threat to its (European) national security.

Relations between Russia and the West have deteriorated since Putin sent his forces to Ukraine to launch a military operation there on February 24.

The United States, Britain and France on Monday criticized Russia for its "irresponsible and dangerous" statements about the possible deployment of nuclear weapons.

Since the start of Russia's intervention in Ukraine, Putin has issued veiled threats indicating the possibility of Russia deploying tactical nuclear weapons, which the Russian military believes it may use to force the opponent to retreat.

Biden's invitation

For his part, US President Joe Biden called on Russia and China on Monday to participate in talks aimed at limiting the spread of nuclear weapons, noting that Moscow in particular should take responsibility after its military operation in Ukraine.

In a statement, the US president said his administration was prepared to "quickly negotiate" an alternative to the New START treaty that ends the intercontinental nuclear power of the United States and Russia, which expires in 2026.

"Russia must show that it is ready to resume work on controlling the spread of nuclear weapons," Biden said.

"But negotiation needs a partner who has the desire and acts in good faith. The brutal and unjustified Russian aggression in Ukraine has broken peace in Europe and represents an assault on the basic principles of the international order," he added.

Speaking of China, which is bolstering its much smaller nuclear arsenal, Biden said the communist country has a duty as a permanent member of the UN Security Council to "engage in talks that reduce the risk of any uncalculated steps and deal with a destabilizing military dynamic."

"None of our countries or the world will benefit from resisting substantive participation in arms control and nuclear proliferation," he added.

The Treaty on the Non-Proliferation of Nuclear Weapons aims to promote cooperation in the peaceful uses of nuclear energy with the goal of nuclear disarmament worldwide.

Since the treaty entered into force in 1970, conferences are held every 5 years to review its implementation.