Putin has dramatically pulled out of a Cold War-era treaty banning short and medium-range nuclear missiles while warning the West to 'expect further steps' as tensions spiral.
Former Russian president Dmitry Medvedev - now deputy head of the country's powerful Security Council - blamed NATO nations for forcing Moscow's hand.
In a fiery post on X, he wrote: 'The Russian foreign ministry's statement on the withdrawal of the moratorium on the deployment of medium- and short-range missiles is the result of NATO countries' anti-Russian policy.
'This is a new reality all our opponents will have to reckon with. Expect further steps'.
Medvedev, who has been exchanging barbs online with US President Donald Trump, gave no details about what those steps entailed.
