WASHINGTON -- Republican presidential nominee Donald Trump says his Democratic opponent, former Secretary of State Hillary Clinton, was responsible for negotiations that led to a $400 million U.S. payment to Iran. Reacting to a Wall Street Journal story published Wednesday that described the delivery of the cash to Tehran in January, Trump accused Clinton on Twitter of having opened talks to give Iran the money.

Trump expanded on his remarks later, saying the money was a ransom payment for four Americans detained in Iran, that Iran released a video of the cash being unloaded from a plane in Tehran and that Iran only released a group of U.S. sailors it had captured in the Persian Gulf because it was about to be paid. These claims range from the incorrect to the unsupported.

TRUMP, in a tweet Wednesday: "Our incompetent Secretary of State, Hillary Clinton, was the one who started talks to give 400 million dollars, in cash, to Iran. Scandal!"

THE FACTS: Trump is wrong about Clinton's involvement. The $400 million payment - plus $1.3 billion in interest to be paid later - is a separate issue from the Iran nuclear deal that Clinton initiated. The process that resulted in the payout started decades before she became secretary of state.

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In the late 1970s the Iranian government, under the U.S.-backed shah, paid the United States $400 million for military equipment. The equipment was never delivered because in 1979, his government was overthrown, revolutionaries took American hostages at the U.S. Embassy in Tehran, and diplomatic relations between the United States and Iran were severed.

In 1981, the United States and Iran agreed to set up a commission at The Hague that would rule on claims by each country for property and assets held by the other. Iran's claim for return of the equipment payment was among many that had been tied up in litigation before the Iran-U.S. Claims Tribunal, and interest the U.S. owed for holding the money for so long was growing.

Litigation over these claims has continued intermittently for 35 years, with some being settled and others going to the tribunal for judgment. All private U.S. claims before the tribunal have been resolved, with Iran paying more than $2.5 billion to American people and businesses. Some claims remain unresolved.

As secretary of state, Clinton did initiate secret talks with Iran over its nuclear program. After John Kerry succeeded her on Feb. 1, 2013, those secret contacts grew into 18 months of formal negotiations that culminated in the July 2015 nuclear deal.

U.S. officials had expected a ruling on the Iranian claim from the tribunal any time, and feared a ruling that would have made the interest payments much higher. As the nuclear talks progressed, the separate, intermittent talks on the military-equipment claim continued.

On Jan. 17, a day after the nuclear deal was implemented, the United States and Iran announced they had settled the claim, with the U.S. agreeing to pay the $400 million principal along with $1.3 billion in interest. Administration statements at the time made clear that the principal and the interest would be paid separately, but did not specify how the money would be delivered.

Trump is correct that the $400 million was paid in cash and flown to Tehran on a cargo plane. But litigation on the Iranian claim preceded Clinton's tenure as secretary of state by decades and heated up only after she left the job.

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TRUMP: "When they took our sailors, they forced them to their knees and the only reason we got them back is that we hadn't paid the money yet. And that's the only reason we got 'em back. Otherwise, they would've had to wait until I became president."

THE FACTS: There is no evidence that the episode with the sailors was related to the Iran deal or the 1970s payment.

On Jan. 12, four days before the Iran deal was implemented and five days before the payment was delivered, 10 sailors veered off course in two small boats and landed on an island in the Persian Gulf where there's an Iranian military installation. They were held at gunpoint and released the next day after negotiations between Secretary of State John Kerry and Iranian Foreign Minister Mohammad Javad Zarif. The Navy has disciplined many of the sailors and their commanders for the navigation error that led to an international incident.

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TRUMP: "It looks like we paid $400 million for the hostages."

THE FACTS: There is no concrete evidence that the cash payment was, in fact, a ransom.

Critics of the Iran deal, including many senior Republican lawmakers, maintain that the $400 million settlement was a ransom for the release of four private American citizens jailed in Tehran and freed a day after the Iran deal was implemented. Some Iranian officials have suggested the same thing. The Obama administration has flatly denied it has ever paid ransoms, including in this case.

The timing of the prisoner release and the arrival of the payment has given weight to GOP claims. U.S. officials acknowledge that progress in the nuclear negotiations contributed to progress on the settlement of the claim as well as progress in talks on the release of the Americans.

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TRUMP: "Iran provided all of that footage, the tape of them taking that money. ... Over there when that plane landed, top secret ... and they have a perfect tape, done by obviously a government camera and the tape is of the people taking the money off the plane, right. In order to embarrass us further, Iran sent us the tapes, right. It's a military tape, it's a tape. It was a perfect angle, nice and steady, nobody getting nervous because they're gonna be shot."

THE FACTS: Several senior U.S. officials involved in the Iran negotiations said Wednesday they weren't aware of any such footage.