President Donald Trump ordered two nuclear submarines to be strategically positioned in response to what he called “highly provocative statements” from former Russian President Dmitry Medvedev NBC NewsCNN, escalating tensions between the nuclear superpowers on 1 August.

“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 wrote on Truth Social. “Words are very important, and can often lead to unintended consequences, I hope this will not be one of those instances.”

The submarine deployment came after Medvedev made reference to Russia’s Soviet-era automatic, retaliatory nuclear strike capabilities on 31 July, after Trump told Medvedev to “watch his words.”

The exchange began after Medvedev said that “each new ultimatum” that Trump makes toward Russia in pressuring an end to the war in Ukraine.

Trump had previously warned of new sanctions against Moscow if Russia did not demonstrate progress in ending the Ukraine war within 10 days.