Stephen J. Rapp, who served as U.S. ambassador-at-large for war crimes issues from 2009 to 2015, said he was disturbed by Trump's threats to Iran if it does not reopen the Strait of Hormuz and agree to end the war the United States and Israel launched a month ago.

"It makes us a rogue state," said Rapp, who served as chief of prosecutions at the International Criminal Tribunal for Rwanda from 2001 to 2007 and the chief prosecutor of the Special Court for Sierra Leone from 2007 to 2009. He and two other experts in international law who spoke to NBC News said Trump's threats alone could represent a possible war crime.