prisoner swap and unfreezing more than $1 billion in iranian assets. that brought four americans home in 2016. >> i didn't do what obama did, give them $1.8 billion in cash to get back four hostages. >> reporter: but president trump's confrontational stance, exiting the nuclear deal, and sanctioning iran, has not stopped the regime from detaining more americans. has the trump administration policy made it harder for them to bring americans home? >> there's essentially no diplomatic contacts between the united states and iran. high-level sustained contacts. and it is going to take some type of a quid pro quo for iran to release these prisoners. >> reporter: before the u.s. exited the nuclear deal last year, iran refused u.s. requests to set up diplomatic talks about prisoners. recent overtures by iran have gone unanswered. today, the trump administration issued a public call for iran to release innocent american detainees. jeff?