Putin revises Russia's nuclear deterrence doctrine, threatens West

Russian President Vladimir Putin has warned the West that Russia could use nuclear weapons if it was struck with conventional missiles, and that Moscow would consider any assault on it supported by a nuclear power to be a joint attack.

His decision on Wednesday to change Russia's official nuclear doctrine is the Kremlin's answer to deliberations in the United States and Britain about whether or not to permit Ukraine to fire conventional Western missiles into Russia.

Putin, opening a meeting of Russia's Security Council, said that the changes were in response to a swiftly changing global landscape which had thrown up new threats and risks for Russia.

The 71-year-old Kremlin chief, the primary decision-maker on Russia's vast nuclear arsenal, said he wanted to underscore one key change in particular.

"It is proposed that aggression against Russia by any non-nuclear state, but with the participation or support of a nuclear state, be considered as their joint attack on the Russian Federation," Putin said.

"The conditions for Russia's transition to the use of nuclear weapons are also clearly fixed," Putin said, adding that Moscow would consider such a move if it detected the start of a massive launch of missiles, aircraft or drones against it.

Russia reserved the right to also use nuclear weapons if it or its ally Belarus were the subject of aggression, including by conventional weapons, Putin said.

Putin said the clarifications were carefully calibrated and commensurate with the modern military threats facing Russia - confirmation that the nuclear doctrine was changing.