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. 

However, congressional Republicans have characterized the money transfer as ransom to secure the detainees' release, a claim President Obama denied earlier this month.

"It’s time for the Obama White House to drop the charade and admit it paid a $400 million ransom to the world’s leading state sponsor of terrorism," Republican National Committee Chairman Reince Priebus said in a statement. "President Obama has foolishly put a price on the head of every American abroad and it should be no surprise that Iran has since detained more U.S. citizens."

"This wasn’t some nefarious deal," Obama said during an August 4 press conference. "We do not pay ransom for hostages."

The Jounal also reported earlier this month that Justice Department officials objected to the timing of the money transfer, saying it would look like a ransom payment. Those concerns reportedly were dismissed by the State Department.  

The three detainees who were flown to Geneva were Washington Post reporter Jason Rezaian; former U.S. Marine Amir Hekmati; and Christian pastor Saeed Abedini.

Abedini has claimed that he and the other hostages were kept waiting at an Iranian airport for more than 20 hours before their departure. Abedini said he was told by a senior Iranian intelligence official that their departure was contingent on the movement of a second plane.

State Department officials denied Abedini's claims to the Journal, saying the delay was due to issues locating Rezaian's wife and mother, who accompanied him on the flight. 

In response to the initial Journal report, Obama said it was necessary to transact the payment in foreign currency due to U.S. sanctions, which prohibit trading in dollars.

According to the Journal, GOP leaders say they plan to hold hearings on the payment next month, when Congress returns from its summer recess. Rep. Sean Duffy, R-Wis., chair of the House Subcommittee on Oversight and Investigations, last week sent letters to the Justice and Treasury Departments, as well as the Federal Reserve, requesting more information the transaction.

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