Another report that this was indeed a ransom. Congressman Pompeo outlines how it is unlawful to have transfer cash to Iran.
Via Fox News:
U.S. officials held a cargo plane carrying the equivalent of $400 million in cash for Iran until Tehran released three American detainees, the Wall Street Journal reported Wednesday.
The report, which cited U.S. officials and others briefed on the operation, said an Iranian cargo plane was allowed to pick up the money in Geneva, Switzerland once a Swiss Air Force plane carrying the three detainees left Tehran last January.
The White House has claimed that the $400 million payment in euros and Swiss francs was the first installment in a $1.7 billion settlement the Obama administration reached with Iran to resolve a failed 1979 arms deal dating from just before the Iranian Revolution.