The move comes on the 1,000th day of Russia’s offensive on Ukraine and after the United States gave Kyiv permission to use long-range missiles to strike military targets inside Russia.

The new doctrine outlines that Russia will consider using nuclear weapons against a non-nuclear state if they are supported by nuclear powers.

“Aggression by a non-nuclear state with the participation of a nuclear state is considered as a joint attack,” Kremlin spokesman Dmitry Peskov told reporters on Tuesday — a clear reference to Ukraine and its Western backers.

“It was necessary to bring our principles in line with the current situation,” Peskov added, calling the update a “very important” document that should be “studied” abroad.

Russia “has always viewed nuclear weapons as a means of deterrence,” he said, adding that they would only be deployed if Russia felt “forced” to respond.

Putin has issued a string of nuclear threats throughout the almost three-year campaign against Ukraine, triggering concern in the West over rhetoric it has slammed as reckless.

The new doctrine also allows Moscow to unleash a nuclear response in the event of a “massive” air attack, even if it only uses conventional weapons.