A military expert has said it is highly likely Russia will conduct a nuclear test to show off new technology amid the war with Ukraine.
On Monday, the NATO military alliance warned members Vladimir Putin was set to demonstrate his willingness to use nuclear weapons by carrying out a test on Ukraine's border, The Times newspaper reported.
It comes amid reports Moscow has moved a train thought to be linked to a unit of the defence ministry responsible for nuclear munitions.
Justin Crump, CEO of intelligence consultancy Sibylline, has moved to play down fears Putin will launch a real nuclear strike against Ukraine but admitted Russia would probably carry out a test.
Crump, a British Army veteran, told BBC Radio 4’s Today programme: “You have to treat the threat seriously but, that said, at this point in time it’s pretty clear that Russian intent is to keep us nervous.”
He added: “I suspect there’s a high likelihood of a nuclear test of some kind in the Arctic, probably showcasing their new technology.
“That could well happen at this time of year anyway.
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“But, of course, anything like that now will be jumped on as proof that Russia is increasing the tension, is increasing the ante and getting ready to use weapons.”
Crump said any nuclear strike from Russia would result in a conventional response led by the US.
He added: “The use of nuclear weapons is a path to suicide for Russia and that’s a clear message that is being given.
“That said, we said Putin would be stupid to invade Ukraine, and he did it anyway
“Now we’re saying it would be pretty stupid to use nuclear weapons, but we are in an unpredictable situation."
Italian daily La Repubblica reported on Sunday that NATO had sent its members an intelligence report on the movements of the Belgorod nuclear submarine.
When asked about the reports, Kremlin spokesman Dmitry Peskov said Russia did not want to take part in what he cast as Western exercises in "nuclear rhetoric".
Putin has said he is prepared to use “all the means at our disposal” - including nuclear weapons - if his country is threatened, seen as a sign that he could use so-called "tactical" strikes in response to attacks on parts of Ukraine he has annexed.
Tactical nuclear weapons use smaller warheads than strategic nuclear weapons and are more likely to be used on the battlefield.
On Sunday, the UK Defence Secretary Ben Wallace said it was “highly unlikely” that Putin will use nuclear weapons in Ukraine - but warned he is not acting in a “rational” way.
General Sir Richard Barrons, who headed up Britain's Joint Forces Command until his retirement in 2016, said that employment of weapons of mass destruction (WMD) by Russia had to be prepared for.