The White House said Monday the United States has been closely tracking Iranian threats against former President Donald Trump for years and it warned of "severe consequences" if Tehran was to attack any U.S. citizen.

"We consider this a national and homeland security matter of the highest priority, and we strongly condemn Iran for these brazen threats. Should Iran attack any of our citizens, including those who continue to serve the United States or those who formerly served, Iran will face severe consequences," White House National Security Council spokesperson Sean Savett said.