Russia has said that it views comments by French President Emmanuel Macron about extending his country's nuclear deterrent to other European countries as a "threat".
Mr Macron raised the idea during an address to the nation yesterday.
He warned that Russia was a threat for all of Europe, adding that France would have to spend more on defence but would continue to help Ukraine.
President Macron said that European military forces could be sent to Ukraine if a peace agreement was signed to guarantee "respect" of the accord.
He added that his country is "legitimately worried" about the United States shifting its position on the Ukraine conflict under President Donald Trump.
France and the UK are Europe's only two nuclear powers.
Responding, Russian President Vladimir Putin said that some people had forgotten what happened to Napoleon Bonaparte.
He was referring to the French emperor who invaded the Russian Empire in 1812 in a disastrous six-month military campaign that ended in victory for Russia and a major loss of life.
"There are still people who want to go back to the times of Napoleon, forgetting how it ended," Mr Putin said, without mentioning President Macron by name.
Russian Foreign Minister Sergei Lavrov said that his country views President Macron's comments as a "threat".
"Of course it is a threat against Russia. If he sees us as a threat ... and says that it is necessary to use a nuclear weapon, is preparing to use a nuclear weapon against Russia, of course it is a threat," Mr Lavrov said.
He also restated Russia's opposition to European forces being deployed in Ukraine if an agreement is reached to end the conflict, suggesting they would not be impartial.
Russia would consider such troops in the same way as it would view a NATO presence in Ukraine, Mr Lavrov said.
He compared the French President to Napoleon as well as German dictator Adolf Hitler, saying that unlike those leaders, Mr Macron did not openly say he wanted to conquer Russia, but he "evidently wants the same thing".
He is making "stupid accusations against Russia" that Mr Putin has dismissed as "madness and nonsense", Mr Lavrov said.
Earlier, Russian foreign ministry spokeswoman Maria Zakharova said that Mr Macron was "detached from reality" and making "contradictory statements".
Meanwhile, Russia's Defence Minister Andrey Belousov has visited the country's nuclear weapons development laboratory.
He told scientists that the army is looking forward to getting its hands on "new developments" in the near future, according to a defence ministry statement.
