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.

After an ultimatum from US President Donald Trump, the Kremlin responded with threats and referenced the Soviet-era nuclear strike system. In response, the White House deployed nuclear submarines closer to Russia.

President Donald Trump issued a rare threat of nuclear escalation on Friday, saying he had ordered two nuclear submarines to be strategically positioned near Russia in response to what he said were aggressive remarks by Dmitry Medvedev,