joining us from washington, msnbc chief foreign affairs correspondent and host of "aerped mitchell reports" andrea mitchell. the administration now has a secretary of state. >> and, boy, i would guess rex tillerson is thrilled to finally be behind that desk. >> i'll tell you who else is thrilled. the thousands of diplomats who have been waiting for a leader. they are really excited. no one has come in with more good advanced billing than rex tillerson and this at such a time. the white house's blunt warning to arena and putting iran on notice and promising to hold tehran accountable and a dramatic escalation from the obama administration's position and the president tweeting this morning iran has been formally put on notice for firing a ballistic missile should have been thankful for the terrible deal the u.s. made with them. >> reporter: the administration's first foreign policy crisis, iran.