Boris Johnson has said he does not believe Vladimir Putin will use a tactical nuclear weapon in the conflict with Ukraine, as it would be “crazy” to wreak “total disaster” on his own country.

The former prime minister said the act would “immediately tender Russia’s resignation from the club of civilised nations” and plunge the country into a “kind of cryogenic economic freeze”.

He added that he suspects it would trigger an “absolutely hysterical reaction” in Russia itself.

It comes as the Defence Secretary has said momentum on the ground remains with Ukraine, with Crimea expected to come within range of Ukrainian artillery by the end of November.

There have been suggestions that Moscow could attempt to escalate the conflict, but Mr Johnson said he does not think Mr Putin will resort to using a tactical nuclear weapon.

He told Sky News: “I don’t think he will. I think he’d be crazy to do so.

“I think what would happen is that he would immediately tender Russia’s resignation from the club of civilised nations. It would be a total disaster for his country.

“So the current economic punishment that the West has been able to dish out would be massively intensified. Russia would be put into a kind of cryogenic economic freeze.”

Russia Putin
Russian President Vladimir Putin (Mikhail Metzel, Sputnik, Kremlin Pool Photo via AP)

Mr Johnson suggested Mr Putin would also lose a lot of the “kind of middle ground of global tacit acquiescence that he’s had”.

“There’s a lot of willingness to give Putin the benefit of the doubt. That will go the minute he does anything like that,” he said.

“He would also, crucially, I think, lose the patronage of the Chinese. And above all in his own country, I think he would trigger an absolutely hysterical reaction.”

Meanwhile, Mr Johnson said he does not think it is “credible” for Mr Putin to retain the territory his troops still hold in regions such as Kherson, in southern Ukraine.

“I don’t think that’s credible for him anymore,” he said.

This sentiment was echoed by Mr Wallace at a meeting of the Lords International Relations and Defence Committee on Tuesday.

“The direction of travel is that I think it is likely that by the end of this month, the northern part of Kherson will be depleted of Russians or the Russians will have left that part, which brings into range parts of Crimea from long-range artillery that the Ukraine held or the HIMARS-type systems,” he said.