Russian President Vladimir Putin warned on Thursday of a "real" risk of nuclear war if the West escalates the conflict in Ukraine.
In a defiant speech in Moscow, he said his soldiers were advancing in Ukraine and warned the West of "tragic consequences" for any country that dared to send troops to Kyiv.
"They have announced the possibility of sending Western military contingents to Ukraine... The consequences for possible interventionists will be much more tragic," Putin said in his annual address to the nation.
"They should eventually realise that we also have weapons that can hit targets on their territory. Everything that the West comes up with creates the real threat of a conflict with the use of nuclear weapons, and thus the destruction of civilisation."
His comments appeared to be a response to French President Emmanuel Macron's refusal earlier this week to rule out sending troops to Ukraine — a refusal that drew rejection from leaders in Europe.
Western leaders have repeatedly criticised Putin for what they see as his reckless use of nuclear rhetoric since Moscow launched its full-scale military offensive against Ukraine.
After pulling Russia out of arms control treaties with the US and previously warning he was "not bluffing" when he said he was ready to use nuclear weapons, Putin had appeared in recent months to dial down his nuclear threats.
But the fresh warning comes with the Kremlin buoyed by recent gains on the battlefield in Ukraine, an economy that has largely defied sanctions, signs of Western support for Ukraine fraying and ahead of an election certain to extend his term in the Kremlin until 2030.
US authorities denounced Putin's comments, adding that there appeared to be no sign of greater nuclear risk.
"It is not the first time we have seen irresponsible rhetoric from Vladimir Putin. It is no way for the leader of a nuclear-armed state to speak," US State Department spokesman Matthew Miller told reporters.
"We have communicated in the past privately and directly with Russia about the consequences of the use of a nuclear weapon.
"We do not have any sign that Russia is preparing to use a nuclear weapon."
