of north korea where he threatened and threatened and threatened some sort of aggressive all-out nuclear war on twitter and increasely abusive of kim jong-un, did a 180 degree turn and did a handshake photo op in singapore. my concern is he'll do the same, that he has now very briefly tweeted one all caps threat at president rouhani of the iranian islamic republic and will declare himself capable of concocting some better deal. the iran nuclear agreement which took years to put together and relied upon our european allies and china and russia isn't something you can replace with a few tweets and photo op. >> when you see a tweet like that one from the president threatening iran in all caps, what's your reaction to it? >> i shake my head.