US President Donald Trump warned that Iran would face severe consequences if the Islamic Republic restarts its nuclear program one day after the US withdrew from the 2015 Iran nuclear deal.

"Iran will find out,"Tru,p said I don't think they should do that. I would suggest Iran not to start their nuclear program. I would advise them very strongly. If they do, there will be very severe consequences."

Trump called the 2015 agreement, known as the Joint Comprehensive Plan of Action (JCPOA) an "embarrassment" that "should never have been reached" during his address Tuesday.

Trump also began the process of reinstating sanctions on Iran which had been lifted under the JCPOA.