Risks of all-out nuclear war appear to have ratcheted up amid an escalation in the Russia-Ukraine war, with a figure close to President Vladimir Putin claiming they could strike a NATO country with a "limited use" of nuclear weapons and get away with it.

A former adviser to Putin, Sergei Karaganov, told Russian newspapers that they had a "right to respond" to any strikes deep inside their territory. Separately, Putin has warned that Western weapons being used to hit targets inside Russia would put the NATO alliance "at war" with his country.

The threat of nuclear armageddon from a key figure close to the Kremlin is in response to growing calls for the US and UK to approve Ukraine's use of long-range Storm Shadow missiles to strike targets far inside Russian territory. This threat has long been the main reason that Ukraine's allies have barred them from striking Russia with Western-made weapons - and Putin wants NATO to know it is still an option.

Arguing for the first use of nuclear annihilation since the end of World War 2, Karaganov told Kommersant: “The assertion that any limited use of nuclear weapons will necessarily lead to a general nuclear Armageddon does not stand up to criticism.”

He went on to claim that the NATO alliance would not retaliate should a small number of nuclear weapons be used, iNews reports, stating that the US is lying about nuclear protection, which was a key reason for the alliance's original formation.

Taking a suitably apocalyptic view of Russia's options, should Western ballistic missiles start striking targets deep into its vast territory, the Putin ally added: “I am not calling for a dangerous path, I am calling for saving the world and Russia. Either we win this war, or we fall apart.”

However, Ukraine's President Zelensky has long called Russia's bluff on threats that it will drop a nuke on civilians, while slowly stepping up the number of drone and missile strikes on his enemy's infrastructure and military targets. This week with both US and UK officials visiting the country, he has renewed his call to be allowed to use the long-range ballistic Storm Shadow.

He told reporters: “If I am optimistic about their decision to give us permission to use long distance, it is a pity it doesn’t depend on my optimism. It depends on their optimism. Let’s count on some strong decisions on this."

There had been a brief moment of diplomatic confusion after Prime Minister Sir Keir Starmer's first meeting with President Zelensky, where the use of these British-designed and American-made missiles was brought up. Leaving the meeting, the Ukraining leader thought he had just got permission to strike Russian targets and tweeted to the effect.

But a Government spokesperson was quick to deny this and say that discussions were still ongoing, amid the Kremlin threat of all-out nuclear war should the West get further involved in the conflict.

However, following a US-UK-Ukraine meeting on Wednesday with Secretary of State Antony Blinken and Foreign Secretary David Lammy, the likelihood that Storm Shadow missiles will be approved for use inside Russia has reportedly grown. In response to this step towards a greater counteroffensive from Ukraine, the Putin ally spelled out the Kremlin's position.

Karaganov said that Putin would have the “right to respond to any massive strikes on our territory with a nuclear strike”.

This would not even need to have a military purpose, but act as a warning. He said the nukes “should be to ensure that all current and future enemies are sure that Russia is ready to use nuclear weapons”.