The Kremlin has tried to calm tensions in a feud between Trump and Medvedev that spiraled into nuclear threats.

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.

Moscow downplayed President Trump's announcement that he'd ordered two nuclear submarines to "the appropriate regions" after heated Russian rhetoric.