LONDON -- The CIA director says it would be an act of “folly” for U.S. President-elect Donald Trump to scrap the nuclear deal with Iran.

John Brennan told the BBC in an interview broadcast Wednesday that it would be “disastrous” to end the deal designed to prevent Iran from developing nuclear weapons.

Mr. Trump threatened during the campaign to scrap the deal. Brennan said doing so would strengthen hardliners in Iran and possibly spur other countries to pursue nuclear weaponry.

Former Director of Central Intelligence Robert Gates, who was also defense secretary under both George W. Bush and Barack Obama, told “CBS This Morning” Wednesday that he largely agreed with Brennan’s assessment.

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“I think it would be a mistake to tear up the agreement at this point. I think we would be the ones isolated, not the Iranians because none of our partners that helped negotiate that would walk away from it,” Gates said.

“But what I do think the next president can do is push back against the Iranians in all of the other activities — in their behavior in the region and you know, pointing guns at our helicopters and challenging our ships and their meddling in Yemen, their meddling in Syria and having significant troops. We should’ve from the very beginning made it clear that we — we’re not going to allow that the agreement on nuclear materials was not going to inhibit us in the slightest from protecting our friends and our interests in that region against the Iranians,” said Gates.

In his interview with the BBC, Brennan also suggested Mr. Trump should be careful in his dealings with Russia.

“I think President Trump and the new administration need to be wary of Russian promises,” Brennan said, noting that Moscow has not always delivered.

He said Russia and the Syrian regime are responsible for the horrendous humanitarian situation facing Syrian civilians. “I do not have confidence that the Russians are going to relent until they are able to achieve as much tactical battlefield successes as possible,” Brennan said.

Brennan plans to step down in January.