VIENNA, AUSTRIA -- U.S. and Iranian officials say Iran is releasing four detained Iranian-Americans in exchange for seven Iranians held or charged in the United States.
A fifth Iranian-American was also expected to be released, but was unrelated to the prisoner swap.
The major diplomatic breakthrough was announced Saturday as the implementation of a landmark nuclear deal appeared imminent.
U.S. officials say the four Americans, including Washington Post reporter Jason Rezaian, former Marine Amir Hekmati and pastor Saeed Abidini, were to be flown from Iran to Switzerland on a Swiss plane and then brought to a U.S. military base in Landstuhl, Germany, for medical treatment.
In return, the U.S. will either pardon or drop charges against seven Iranians - six of whom are dual citizens - accused or convicted of violating U.S. sanctions. The U.S. will also drop Interpol "red notices" - essentially arrest warrants - on a handful of Iranian fugitives it has sought.