Russian President Vladimir Putin has warned that Russia could respond with nuclear weapons if it were attacked with conventional arms in the latest changes to the country’s nuclear doctrine.

In a televised meeting of Russia’s Security Council, Putin announced that under the planned revisions, an attack against the country by a non-nuclear power with the “participation or support of a nuclear power” would be seen as a “joint attack on the Russian Federation”.

Putin emphasised that Russia could use nuclear weapons in response to a conventional attack that posed a “critical threat to our sovereignty”, a vague formulation that leaves broad room for interpretation.

The Russian president is the primary decision-maker on Russia’s nuclear arsenal and needs to give his final approval to the text.

The change appears to significantly lower the threshold for Russia to use atomic weapons and comes as Ukraine’s Western allies consider whether to allow Kyiv to use longer-range weapons to strike military targets deep inside Russia, and a month after Kyiv launched a surprise incursion into Russia’s Kursk region.

Putin did not refer to Ukraine directly, but said the revisions to the doctrine were necessary in view of a swiftly changing global landscape that had created new threats and risks for Russia.

Russia is making slow but incremental gains in Ukraine since it launched its full-scale invasion of the country two and a half years ago and is trying to dissuade Kyiv’s Western allies from strengthening their support.

Putin has made several implicit threats of nuclear attack since launching his war and has suspended Russian participation in the the New START treaty with the US, which limits the number of nuclear warheads each side can deploy.

Ukraine President Volodymyr Zelenskyy has urged Western powers to disregard Russia’s threats, and his chief of staff, Andriy Yermak, said Putin’s latest remarks were little more than blackmail.

“Russia no longer has any instruments to intimidate the world apart from nuclear blackmail,” Yermak said. “These instruments will not work.”

‘Never good’

Russia’s existing nuclear doctrine, set out in a 2020 decree, says Moscow could use its nuclear arsenal in case of a nuclear attack by an enemy or a conventional attack “when the very existence of the state is in jeopardy”.

Russia’s hawks have been calling for toughening the doctrine for months, claiming the current version is too vague and leaves the impression that Moscow would not ever resort to using nuclear weapons.

Putin stressed the revised doctrine spelled out conditions for using nuclear weapons in greater detail, and that they could be used in case of a massive air attack.

“Conditions for Russia’s move to use nuclear weapons are clearly stated” in the revisions, he said.

“We will consider such a possibility when we receive reliable information about a massive launch of air and space attack assets and them crossing our state border,” Putin added, citing “strategic and tactical aircraft, cruise missiles, drones, hypersonic and other flying vehicles”.

The current version of the document states Russia would use its nuclear arsenal if its receives “reliable information is received about the launch of ballistic missiles targeting the territory of Russia or its allies”.

Ukraine has repeatedly struck Russian territory with missiles and drones in response to Moscow’s attacks.

“Regardless of whether you think this is a bluff or not, it’s never good when a major nuclear power loosens the conditions for nuclear use in its declaratory policy,” said Samuel Charap, senior political scientist at RAND, in a post on X.

Putin also said the revised doctrine would bring neighbouring Belarus under Russia’s nuclear umbrella.

President Alexander Lukashenko, a Putin ally who has ruled Belarus for more than 30 years, has let Moscow use his country’s territory to send troops into Ukraine. He has also allowed the Kremlin to deploy some of Russia’s tactical nuclear weapons there.

Russia is the world’s largest nuclear power. Together, Russia and the US control 88 percent of the world’s nuclear warheads.