House Speaker Paul Ryan, R-Wis., said Obama "owes the American people a full accounting of his actions and the dangerous precedent he has set."



The money came from an account used by the Iranian government to buy American military equipment in the days of the U.S.-backed shah. The equipment was never delivered after the shah's government was overthrown in 1979 and revolutionaries took American hostages at the U.S. Embassy in Tehran. The two sides have wrangled over that account and numerous other financial claims ever since.



The Jan. 17 agreement involved the return of the $400 million, plus an additional $1.3 billion in interest, terms that Obama described as favorable compared to what might have been expected from a tribunal set up in The Hague to rule on claims between the two countries. U.S. officials have said they expected an imminent ruling on the claim and settled with Tehran instead.



At an Aug. 4 news conference at the Pentagon, Obama said nothing nefarious occurred.



"We do not pay ransom for hostages," he said.



In a conference call with reporters, two senior administration officials intimately involved with the financial and prisoner negotiations sought to refute what they described as false reports about what happened. They weren't authorized to speak publicly on the matter and demanded anonymity.



There was no way that Washington could have avoided repaying the money to Iran in the short-term, one of the officials insisted.



The 1981 Algiers Accord between the U.S. and Iran that set up the tribunal made repayment mandatory, and allowed for either claimant to seize assets in international courts if the other reneged on a ruling, the official said. Iran had lived up to its commitment by repaying $2.5 billion awarded for claims by U.S. citizens and companies.



A ruling on the military fund was expected soon, the official said, as Iran asked last year for the tribunal to hear its case and Tehran and Washington had been negotiating proposals for a hearing. Given that interest rates in the early years of the fund were as high as 20 percent, the official said Iran stood to receive a much more substantial award than $1.3 billion in interest. As a result, the U.S. opted to settle with Iran.



The second American official argued that if there was any quid pro quo, it was the exchange of U.S. and Iranian prisoners. Washington released seven Iranians, mostly dual Iranian-American nationals convicted of sanctions violations, as part of the deal.



But even that trade-off faced several difficulties on the busy diplomatic weekend in January that also included the Iranians complying with last year's nuclear accord and the U.S. lifting many oil, trade and banking sanctions on Iran — context, the official said, that played into the administration's decision making with the $400 million.



He said the wife of one of the prisoners, Washington Post reporter Jason Rezaian, went "incommunicado" for several hours even though Iran had agreed to allow her to join her husband on the plane.