A former NATO Secretary General believes Vladimir Putin's threat of nuclear war is merely bluster.
Lord Robertson of Port Ellen told BBC Radio 4's World At One programme to be wary of the Russian leader's insistence his threats are "not a bluff".
Robertson said: "I think it's bluster. I think it hides a genuine weakness now in the Russian position in relation to what is happening in Ukraine.
"I think we are going to hear the rhetoric stepped up, because on the battlefield they don't seem to be able to make the progress that they claim."
Russian troops are struggling in Ukraine and appear to be on the back foot in the face of a counteroffensive.
Ukraine has made some significant gains recently and is looking to liberate its territory in the Donbas and in Crimea; the latter was annexed by Russia in 2014.
NATO's top official from 1999 to 2003 added that dealing with Russia was much easier when he was part of NATO, but times have changed drastically since.
Robertson even signed the 2002 Rome declaration with Putin, which worked to try and establish good relations between NATO partners in the West and Russia
He added: "It's much more dangerous than it was in my time. Russia was on side with us, Russia was a partner with us, we were doing good business with President Putin.
"I signed the Rome declaration with him in 2002, which said that individual countries had the sovereign right to make their own decisions on security.
"But, in the meantime, a lot has changed including the psychology of the man in the Kremlin.
"So, it's a much more dangerous world when somebody so mercurial as President Putin can be taking these kind of life and death decisions for his country, and indeed for the world."
Putin has operated to make the situation in the region extremely complicated and, as Ukraine pushes its counteroffensive, referendums look set to be held in the regions of Donetsk, Luhansk, Zaporizhzhia and Kherson.
Any referendums are likely to be an undemocratic sham that Russia may use as a basis to annex the territories.
With the Kremlin leader issuing nuclear threats, this may be of particular concern if Russia deems itself justified in using nuclear weapons to protect its perceived territory.
He said: "If the territorial integrity of our country is threatened, to defend Russia and our people, we will use all means we have. This is not a bluff.
"The territorial integrity of our motherland, our independence and freedom will be secured, I repeat, with all the means we have. Those who try to blackmail us with nuclear weapons should know that the prevailing winds can turn in their direction."
