FILE -- In this Dec. 18, 2007, file photo, Christine Levinson, left, the wife of a missing American former FBI agent, her son, Daniel, and her sister Susan exit Tehran's Imam Khomeini airport upon their arrival in Iran. The family of Robert Levinson, who went missing in Iran a decade ago on an unauthorized CIA assignment, filed a lawsuit Tuesday, March 21, 2017, against Iran. The lawsuit in U.S. federal court describes in detail offers by Iran to “arrange” for his release in exchange for a series of concessions, including for the return of a Revolutionary Guard general who defected to the West.. (AP Photo/Vahid Salemi, File)