The Kremlin said on Thursday that changes to Russia's nuclear weapons doctrine outlined by President Vladimir Putin should be considered a signal to Western countries that there will be consequences if they participate in attacks on Russia.

Putin said on Wednesday that Russia could use nuclear weapons if it was struck by conventional missiles, and that Moscow would consider any assault on it supported by a nuclear power to be a joint attack.

The decision to change Russia's official nuclear doctrine is the Kremlin's answer to deliberations in the United States and Britain about whether to give Ukraine permission to fire conventional Western missiles into Russia.