In an unexpected move, $3 billion of Iranian assets frozen in Iraq under US sanctions were released. The move comes shortly after Tehran denied reports that it was about to reach an agreement with Washington to lift some sanctions.

What is the secret behind this and what is the impact of this measure on the nuclear agreement between Iran and the United States? The full interview will be broadcast on CNN at 9 p.m. ET on Thursday, July 26. For more information on CNN's coverage of the Iran nuclear crisis click here.