Donald Trump says the Iran nuclear deal would force the United States to defend Iran if it were attacked by Israel.

He denounced the deal as "horrendous" during a Sept. 3 radio interview on "The John Fredericks Show," a Hampton Roads-based broadcast that’s aired through much of Virginia.

Trump added: "If Israel attacks Iran, I think -- of course this wouldn’t happen, it wouldn’t happen with me, with Obama you never know -- but we’re supposed to be on Iran’s side if this happens. OK? And nobody knows this and even talks about that point but, basically, we’re supposed to protect them."

The Republican front-runner for the White House made similar comments a day earlier during a CNN interview .

"You know, there is something in the Iran deal that people I don't think really understand or know about," he said. "And nobody is able it to explain it, that if somebody attacks Iran, we have to come to their defense."

Trump’s comments come on the heels of events that all but guarantee the U.S. will participate with other nations in a deal in which Iran will curb its short-term nuclear ambitions in exchange for a lifting of economic sanctions.

Sen. Barbara Mikulski, D-Md., announced her support for the accord on Sept. 2, making her the 34th senator to do so. That means opponents will be unable to muster the two-thirds vote necessary to override President Barack Obama’s pledged veto of a congressional vote to defeat the deal.

We asked Trump’s campaign for backup on the candidate’s statements and didn’t hear back. But the claim is familiar to PolitiFact; it also has been made by U.S. Sen. Marco Rubio , R-Fla., and debated in Israel. Let’s zero in.

The Iran deal

At the heart of the claim is Article 10, Annex III , of the accord which states:

"E3/EU+3 parties, and possibly other states, as appropriate, are prepared to cooperate with Iran on the implementation of nuclear security guidelines and best practices."

That includes the following:

• "Co-operation in the form of training courses and workshops to strengthen Iran's ability to prevent, protect and respond to nuclear security threats to nuclear facilities and systems as well as to enable effective and sustainable nuclear security and physical protection systems;

• "Co-operation through training and workshops to strengthen Iran’s ability to protect against, and respond to nuclear security threats, including sabotage, as well as to enable effective and sustainable nuclear security and physical protection systems."

This article has been criticized in the Israeli media.

"One of the clauses in the nuclear deal reached between world powers and Iran last week guarantees that the world powers will assist Iran in thwarting attempts to undermine its nuclear program," Israel Hayom , a newsletter, said July 20.

But experts told PolitiFact Florida in late July that such interpretations are, at best, exaggerated. The aim of the provision, they said, is to protect nuclear materials from theft (say, if terrorists tried to steal Iranian assets) or from sabotage (with the intent of causing a hazardous-materials threat to health).

For years, in both Republican and Democratic administrations, the United States has pushed countries around the world to improve security for their nuclear material and facilities, said Matthew Bunn, a professor at Harvard and an expert on nuclear theft and terrorism. This agreement furthers that goal, he said.

"It has nothing to do with helping Iran protect its nuclear facilities from a military attack" of the kind that Israel or Egypt might carry out, Bunn said. "It’s about protecting against thieves and terrorists who might want to steal nuclear material or sabotage a nuclear facility."

Bunn added that by its plain language, the provision does not obligate any of the signatories, including the United States, to do anything in particular. Rather, it says the signatories are "prepared" to cooperate with Iran on these topics, with lots of wiggle room for all sides.

"My guess is that very little cooperation in these areas will take place," Bunn said. Russia and China might be willing to do some training, but nothing would force the United States to do so.

If the United States did participate, there’s even some historical precedent for intelligence gains from this sort of activity, Bunn said. He said American cooperation with Russia after the collapse of the Soviet Union dramatically reduced the risk that nuclear material would be stolen and gave the U.S. insights into the Russian nuclear complex.

Meanwhile, the agreement allows -- but doesn’t mandate -- training for Iran in protecting against threats such as cyber-sabotage. Some see this as ironic because of reports that Obama secretly ordered the Stuxnet computer virus to be launched against Iran to derail its nuclear program. But it’s hard to believe that the U.S. would share its secrets in this realm, and the agreement doesn’t force them to do so.

"Do you seriously think that any training we might offer Iran would help them ward off another Stuxnet?" Bunn said. "This is really silly. There are good arguments on both sides about this agreement, but this isn’t one of them."

Richard Brennan, a senior political scientist at the RAND Corp. and a career Army officer, agreed that the deal doesn’t prevent the U.S. from attacking Iran using cyber or other means or require the U.S. to develop measures to counter a future cyber attack.

"The intent (of the provision) is to make certain that Iran is capable to protect nuclear materials from falling into the wrong hands and help it prevent sabotage," he said.

The administration has been clear about how it interprets this provision. Rubio quizzed Secretary of State John Kerry on this portion of the deal during a Senate Foreign Relations Committee hearing July 23. The exchange occurred one day after Rubio told Fox News that the accord would force the U.S. to defend Iran if Israel or "any other country tries to undermine" Iran’s nuclear facilities.

Here is an excerpt:

Rubio: "If Israel conducts an airstrike against a physical facility, does this deal, the way I read it, does it require us to help Iran protect and respond to that threat?"

Kerry: "No."

Rubio: "If Israel conducts a cyber attack against the Iranian nuclear program, are we obligated to help them defend themselves against the Israeli cyberattack?"

Kerry: "No, I assure you, that we will be coordinating very, very closely with Israel as we do on every aspect of Israel’s security."

Our ruling

Trump said that under the Iran deal: "If Israel attacks Iran … we are supposed to be on Iran’s side."

The claim rests on an interpretation of a provision that the U.S. and other partners are prepared, "as appropriate," to cooperate with training to strengthen Iran’s ability to protect against and respond to nuclear security threats, including sabotage.

But the White House has made it clear that its interpretation of the provision is that it is targeted at terrorists and saboteurs, not Israel or other U.S. allies. If you’re still in doubt, consider that nothing in the provision compels the U.S. to offer any assistance to Iran in the event of a threat to its nuclear program.

So we rate Trump’s statement False.