London, Washington-The United States has acknowledged that it waited for Iran to release American prisoners before delivering $400 million in cash that it owed the country, but again insisted the payment was not ransom.

“With concerns that Iran may renege on the prisoner release… we of course sought to retain maximum leverage until after American citizens were released,” State Department spokesman John Kirby told reporters.

“That was our top priority,” he said.

President Barack Obama, Secretary of State John Kerry and other officials in the U.S. administration had denied the connection between the release of the American prisoners in January and the airlift of $400 million in cash to Iran.

On Thursday, The Wall Street Journal revealed new details on the deal, saying it depicts a tightly scripted exchange specifically timed to the release of the American prisoners.

“The picture emerged from accounts of U.S. officials and others briefed on the operation: U.S. officials wouldn’t let Iranians take control of the money until a Swiss Air Force plane carrying three freed Americans departed from Tehran on Jan. 17. Once that happened, an Iranian cargo plane was allowed to bring the cash home from a Geneva airport that day,” the newspaper said.

Kerry said in early August that the cash delivered to the Iranian government at the same time a complicated nuclear deal was settled and the Americans were released was unrelated and not a ransom.

“The United States does not pay ransom and does not negotiate ransoms,” Kerry told reporters in Buenos Aires, Argentina.

He said the settlement agreement ultimately saved U.S. taxpayers what could have been billions of dollars in additional interest.

At a wide-ranging press conference at the Pentagon, Obama also expressed surprise at criticism of his administration’s cash payment to Iran, adamantly rejecting claims that it was a ransom.

“We do not pay ransom for hostages,” Obama said.

The Wall Street Journal said the payment was aimed at resolving a dispute linked to a trust fund that Iran used before the 1979 Islamic revolution to busy U.S. weapons.

Republicans, including Donald Trump, pounced on Thursday’s admission as proof that Obama’s government had misled the American people.

“Speaking of lies, we now know from the State Department announcement that President Obama lied about the $400 million dollars in cash that was flown to Iran,” Trump said.

“He denied it was for the hostages, but it was. He said we don’t pay ransom, but he did. He lied about the hostages – openly and blatantly,” Trump added.

His opponent in the race for the White House, former secretary of state Hillary Clinton, was no longer serving as the nation’s top diplomat when the accord came into effect.

Still, Trump senior communications advisor Jason Miller said that “by helping put together a deal that ultimately sent $400M to Iran that was likely used to fund terrorism, Clinton has proven herself unfit to be president of the United States.”