new hard-hitting sanctions on tehran top leaders. adding the move was partly in retaliation for the downing of a u.s. drone last week. >> this, you could probably steve, add that into it but this is something that would happen anyway. >> reporter: as he's done in the past with other adverse air yours, the president said more tough action could be on the way if iran doesn't change its behavior. >> i won't say what i will do but i don't think they should do it. >> reporter: but it is the brinksmanship the president has used before with mixed results. consider what mr. trump discussed moments after he unveiled the sanctions on iran. that he's just received a birthday message from north korean dictator kim jong-un. the same man he once dubbed little rocket man. kind of bravado that doesn't always lead to big wins. >> he sent me birthday wishes but it is a friendly letter both ways. >> reporter: the president pulled back from his threats to round up undocument the migrants and tweeting he's delayed for two weeks to see if congress