Speaking at Russia's flagship economic forum in St Petersburg, Putin said Russian tactical nuclear warheads had already been delivered to Belarus, but stressed he saw no need for Russia to resort to nuclear weapons for now. 

The move, Moscow's first deployment of such warheads - shorter-range nuclear weapons that could potentially be used on the battlefield - outside Russia since the fall of the Soviet Union was intended as a warning to the West about arming and supporting Ukraine, Putin said.

The United States has criticised Putin's decision but has said it has no intention of altering its own stance on strategic nuclear weapons and has not seen any signs that Russia is preparing to use a nuclear weapon.