UK Defence Secretary Ben Wallace sought to reassure Europe on Sunday, saying Russian President Vladimir Putin was “highly unlikely” to use nuclear weapons in the Ukraine conflict.
But Mr Wallace said Mr Putin was not acting in a “rational” way.
There have been fears he could use tactical nuclear weapons in response to attacks on parts of Ukraine he has annexed after he vowed to use “all the means at our disposal” if his country is threatened.
In a fringe meeting at the Conservative party conference, Mr Wallace said that although the use of nuclear weapons was in the Russian military doctrine, it would be unacceptable to Moscow’s allies, India and China.
He told the event, hosted by the Onward think tank, that Mr Putin “was given a very clear sense what is acceptable and unacceptable” in meetings with the Indian and Chinese leaderships.
But Mr Wallace said the Russian leader’s actions, from the nerve agent attack in Salisbury to the invasion of Ukraine, were “totally irrational”.
In a sign of the latest concerns about Russia’s actions, he3 will join a crisis meeting of northern European nations on Monday to discuss the security of pipelines and undersea cables.
Vladimir Putin annexes four regions of Ukraine - in pictures
British Prime Minister Liz Truss said explosions that caused major damage to Russia’s undersea Nord Stream gas pipelines were “clearly an act of sabotage”.
Mr Wallace said the UK and the Nordic nations were “deeply vulnerable” to acts of sabotage against cables and pipelines.
“I’ll be convening, with the Dutch, a virtual joint expeditionary force meeting on Monday,” he said.
“So I have to break my timetable tomorrow to meet 10 of the Nordic states about what we’re going to do about it because the Nordic states and ourselves are deeply vulnerable to people doing things on our cables and our pipelines.
“So suddenly, that becomes a big issue we have to get to the bottom of.
"We have to think about what assets we can move to give people reassurance or, indeed, investigate what’s going on.”
Mr Wallace said the prolonged war in Ukraine had shown the need to make sure stockpiles of equipment and supply chains were protected, as he admitted some supplies were running “fairly low”.
Defence spending had been “hollowed out” over 30 to 40 years so “unsexy parts” of the budget had been neglected, he said.
Putin's inner circle – in pictures
Mr Wallace acknowledged that “some of our weapons stockpiles are fairly low and the supply chains switched off 10 years ago, so we have to reinvigorate that”.
He said the Russians were suffering badly, in part because some of their suppliers were in Ukraine and had been bombed — a sign of the “strategic genius that President Putin is clearly proving to be”.
Mr Wallace also said the government had committed to “two specialist ships” that can patrol and protect underwater infrastructure from Russia.
He told members the “mysterious” damage inflicted to the Nord Stream pipelines this week should be a reminder of how fragile the UK economy and infrastructure are in the face of “hybrid attacks”.
Mr Wallace warned that Russia makes “no secret” of its ability to target underwater infrastructure.
He said the UK would acquire the two ships to protect the network as “our internet and energy are highly reliant on pipelines and cables”.
“Our intent is to protect them … Russia makes no secret of its ability to target such infrastructure," Mr Wallace said.
“So for that reason, I can announce we recently committed to two specialist ships with the capability to keep our cables and pipelines safe.
“The first multi-role survey ship for seabed warfare will be purchased by the end of this year, fitted out here in the UK and then be operational before the end of next year.
“The second ship will be built in the UK and we will plan to make sure it covers all our vulnerabilities.”
The Kremlin was accused of attacking the Nord Stream pipelines beneath the Baltic Sea, which led to huge methane leaks.
Mr Wallace also said he has not ruled out a future bid for the Tory leadership and admitted being head of Nato would be a “nice job”.
He did not run in the contest in which Ms Truss was elected, instead insisting he was focused on his departmental responsibilities.
But he remains a popular figure within the party, bolstered by his handling of the Ukraine war.
He said leading the party and becoming prime minister would have meant “sacrificing everything”.
“You have to really, really want it to be a prime minister," Mr Wallace said. "I think you have to really want to sacrifice absolutely everything, and I mean in your private and your personal life.
“It doesn’t mean to say I wasn’t tempted. I was conflicted between a deep sense of duty I have to the country I love, to try and do the very best for it, but also I knew I was in a job I felt fulfilled in.
“So at this time in life, the idea was no. I mean, do I rule it out? No, I don’t rule it out. But will I be here in a few years time? I didn’t know either.”
Asked whether he would like to succeed Jens Stoltenberg as Nato secretary general when his term ends in 2023, Mr Wallace said: “I love doing the defence secretary job, I genuinely do. I don’t know how long the prime minister wants me to do it.
“[Nato] would be a nice job, but I love this. I want to hold the prime minister to account on her pledges to defence.
“It was very important to me, when it came to the leadership election, that people recognised that defence spending is not a discretionary luxury at the bottom of people’s priorities, it’s for real.
“The world is very much more unsafe, more unstable. We all worry about our prices and our security of our supply chains.
"That’s not going to happen on its own. We need to invest in security, we have to invest in keeping our people safe.”
The Ukraine war latest - in pictures
At another fringe event, James Cleverly said Ukraine will succeed in pushing out Russian invaders because Moscow’s “tanks are fearful of Ukrainian tractors”.
“We have seen Ukrainians — both their professional army but also those people volunteering, those people, the students and the musicians and the politicians and the artists and the sports stars — taking up arms and defending their country against this illegal, unprovoked act of aggression by Vladimir Putin," Mr Cleverly said.
“Anyone here who was a member of the armed forces, you’re always told the only thing that a tank fears is another tank.
“Well, Russian tanks are fearful of Ukrainian tractors.
“That’s why Ukrainians will succeed, and when they do and when that fantastic, glorious day comes, then our role evolves, because we have to help them rebuild their country and rebuild their society and rebuild their economy.”
Ukraine’s ambassador to the UK said he was “fascinated” by UK bureaucracy as he criticised the visa process.
At a fringe event at the conference held by the Conservative Friends of Ukraine group, Vadym Prystaiko thanked Britons for opening up their homes to Ukrainians fleeing the war.
With the six-month contract under the government’s sponsorship scheme about to expire, Mr Prystaiko asked for “more hospitality, more generosity, more patience” from those putting up refugees.
“We’ll never forget this, this act, this kindness," he said.
“And please, somebody do something with the visas, finally. Where is Secretary Cleverly? This is just a disgrace, you know, I have to tell you.
“I’m fascinated … by your bureaucracy.”
Vladimir Putin says Russia will use 'all means' to defend its territory - video
He has previously urged MPs to drop visa requirements for fleeing Ukrainians and said his wife faced delays in obtaining one.
Meanwhile, former prime minister Boris Johnson was named as the incoming president of the Conservative Friends of Ukraine group.
