U.S. President Donald Trump on Friday said he had ordered two nuclear submarines to be moved in response to "inflammatory statements" 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.

"Words are very important, and can often lead to unintended consequences, I hope this will not be one of those instances."

Trump and Medvedev, who is deputy chairman of Russia's Security Council, traded taunts in recent days after Trump on Tuesday said Russia had "10 days from today" to agree to a ceasefire in Ukraine or be hit, along with its oil buyers, with tariffs.

WATCH | Trump says Russia needs to reach ceasefire with Ukraine or face 'very severe tariffs': 

Trump gives Putin 50-day deadline for Ukraine ceasefire

U.S. President Donald Trump declared a 50-day deadline on Russia to reach a ceasefire with Ukraine or face ‘very severe tariffs.’ Meanwhile, Trump also pledged renewed support for Ukraine — a move welcomed by NATO allies.

Moscow, which has set out its own terms for peace in Ukraine, has shown no sign that it will comply with Trump's deadline.

Medvedev on Monday accused Trump of engaging in a "game of ultimatums" and reminded him that Russia possessed Soviet-era nuclear strike capabilities of last resort after Trump told Medvedev to "watch his words."

Medvedev has emerged as one of the Kremlin's most outspoken anti-Western hawks since Russia sent tens of thousands of troops into Ukraine in 2022. Kremlin critics deride him as an irresponsible loose cannon, though some Western diplomats say his statements illustrate the thinking in senior Kremlin policy-making circles.