U.S. President Donald Trump on Friday said he had ordered two nuclear submarines to be moved to the "appropriate regions" in response to threats 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 that called Medvedev’s statements highly provocative.

"He's elected to assess the foreign affairs situation in the United States and take appropriate action," Jamieson Greer said Sunday.

U.S. President Donald Trump holds a chart next to U.S. Secretary of Commerce Howard Lutnick as Trump delivers remarks on tariffs in the Rose Garden at the White House in Washington, D.C., U.S., April 2,