The US president had traded taunts with the Russian politician over Trump’s deadline for Moscow to agree to a ceasefire in Ukraine

US President Donald Trump on Friday said he had ordered two nuclear submarines to be positioned in “appropriate regions” in response to threats from former Russian president Dmitry Medvedev.

“I have ordered two Nuclear Submarines to be positioned in the appropriate regions, just in case these foolish and inflammatory statements are more than just that,” Trump said in a social media post that called Medvedev’s statements highly provocative.

He added: “Words are very important, and can often lead to unintended consequences, I hope this will not be one of those instances.”

Trump did not say whether he meant nuclear-powered or nuclear-armed submarines. He also did not elaborate on the locations, which are kept secret by the US military.