THE United Nations has warned that nuclear conflict is now a possibility, as Russia's war in Ukraine continues to escalate.

United Nations Secretary-General Antonio Guterres reacted after Russia’s decision to raise the alert level for its nuclear forces after invading Ukraine He said the prospect of nuclear conflict is now back within the realm of possibility.

And an ex-RAF chief Air Marshal Edward Stringer has admitted that the possibility of nuclear war would be "weight on the minds" of world leaders. He said sanctioning the deployment of nuclear weapons was "in the realms of possibility" and "only a few steps away'".

The warnings come amid growing fears the conflict in Ukraine could escalate to a World War Three involving nuclear weapons.

“The prospect of nuclear conflict, once unthinkable, is now back within the realm of possibility,” Mr Guterres said.

Russia’s invasion of Ukraine that began on February 24 has so far sent more than 2.8 million people fleeing across Ukraine’s borders and trapped hundreds of thousands in besieged cities while triggering broad sanctions on Russia.

Russian President Vladimir Putin late last month said that his nation’s nuclear forces should be put on high alert, raising fears that Russia’s invasion of Ukraine could lead to nuclear war.

US officials have said they have seen no reason so far to change Washington’s nuclear alert levels.

And other experts have been quick to point out that the risk of mutually assured destruction has always been the biggest deterrent against using nuclear weapons and has kept rogue nations from pressing the button.

The Herald:

Mr Putin put Russia's strategic nuclear weapons forces on high alert on February 27, prompting fears over what could happen next in the conflict in Ukraine.

Defence Secretary Ben Wallace has attempted to pour cold water on fears of a nuclear war, stating last month that while he understood the concerns, the phrasing is a "battle of rhetoric".

Russia and the United States have by far the biggest arsenals of nuclear warheads after the Cold War that divided the world for much of the 20th century, pitting the West against the Soviet Union and its allies.

Mr Stringer, the former Director-General of Joint Force Development at Strategic Command and RAF Assistant Chief of Air Staff, when asked of the chance of nuclear war said: "It's no longer unthinkable and it will clearly be weighing on the minds of those who are making all the political calculations at the moment, hence the very straight and consistent line from Biden and all the other senior heads of state recently."

He added: "It's in the realms of possibility, and that's what people have to get their heads around."

He said could "sketch a plausible chain of events" that may lead to nuclear war, which is "only a few steps to get from where we are now".

He said: "And that is why when there were calls for no-fly zones, the political leadership was quick to point out that Nato is a defensive alliance, Nato is not being attacked, Nato is not constructed to go onto the offensive, if it did it would be taking on another nuclear power – Russia.

"Russian nuclear doctrine has within it the use of nuclear weapons. That's only a few steps to get from where we are now to a confrontation that could see the use of nuclear weapons, which I think is a pretty terrifying prospect for anybody sensible."

Mr Guterres also called for the preservation of the security and safety of nuclear facilities after a fire at the Zaporizhzhia nuclear power plant in Ukraine, Europe’s biggest of its kind, that broke out during a takeover of the plant by Russian forces.

“It is time to stop the horror unleashed on the people of Ukraine and get on the path of diplomacy and peace,” he said.