Vladimir Putin was so close to launching a nuke in Ukraine in October 2022 that Britain was preparing for the fallout, it is understood.

Former Prime Minister Liz Truss reportedly spent her final days in office examining weather maps and preparing for UK radiation cases after American spies raised concerns that Putin was seriously close to pressing the button.

The shocking details of how close the war came to a devastating escalation have been uncovered in an updated biography of Ms Truss, titled Out of the Blue.

The biography reports that the short-lived PM spent ‘numerous hours studying satellite weather data and wind directions’ over fears the ‘wrong weather patterns’ could have a ‘direct fall-out effect on Britain’.

It comes as Putin has deployed 50,000 Russian and North Korean troops in a bid to seize Kursk from Ukraine before Donald Trump takes office as US president.

The leading military commander in Ukraine said ‘tens of thousands of enemy soldiers’ have arrived to expel Kyiv’s forces from the enclave, sparking concerns in the West of a serious escalation of the conflict by next month.

A British defence intelligent assessment seen by The Telegraph reveals that Russia is anticipated to increase its kamikaze drone attacks on Ukrainian positions very soon, using new launch sites near the border.

Putin is hoping to recapture territory before Trump’s return to office on January 20 next year, Nato allies believe, when he is expected to support talks that could finally bring the war to an end.

Trump reportedly used a phone call with Putin following his election success last week to warn the Russian president against escalating the war.

Russia has already recaptured roughly half the territory lost to Ukraine in an incursion in August.

Yesterday, Putin denied reports he had spoken with Trump in recent days and added he has no concrete plans yet to speak to him.

The call between the President-elect and Russian leader was first reported by the Washington Post, citing unidentified sources, and said that Trump told Putin he should not escalate the Ukraine war. News agency Reuters also reported on the call, citing an unidentified source.

Trump is said to have warned Putin on Thursday not to escalate the war in Ukraine and reminded him of ‘Washington’s sizeable military presence in Europe’, according to the Washington Post.

But yesterday Kremlin spokesman Dmitry Peskov vehemently denied this call ever took place. ‘This is completely untrue. This is pure fiction, it’s just false information,’ Peskov said as he brutally hit back. ‘There was no conversation.’

‘This is the most obvious example of the quality of the information that is being published now, sometimes even in fairly reputable publications,’ Peskov said.

Asked if Putin had plans for any contacts with Trump, Peskov said: ‘There are no concrete plans yet.’

Putin denying that the phone call took place is awkward for Trump, who has long maintained that he has Putin’s ear, promising to find a resolution to the war in Ukraine.