President Trump is rattling the U.S.’s formidable nuclear saber amid his growing frustration with Russian President Vladimir Putin’s refusal to halt the war in Ukraine, just days ahead of Trump’s deadline for a ceasefire.

The Kremlin warned Monday against “nuclear rhetoric” after President Trump repositioned two nuclear submarines because of what he called “foolish and inflammatory statements” by former Russian president Dmitry Medvedev.

Russia said on Monday that everyone should be "very, very careful" about nuclear rhetoric, responding to a statement by U.S. President Donald Trump that he had ordered a repositioning of U.S. nuclear submarines.