CIA director John Brennan
CIA director John BrennanReuters

CIA Director John Brennan said Sunday no matter the outcome of nuclear talks with Iran, the U.S. will “continue to keep pressure” on the country.

“The nuclear program is one issue that we’re hoping to be able to halt; but also, we see that Iran is still a state sponsor of terrorism,” Brennan said during an exclusive interview on “Fox News Sunday.”

“And so what we have to do, whether there's a deal or not, is continue to keep pressure on Iran and to make sure that it is not able to continue to destabilize a number of the countries in the region.”

Brennan said that in his opinion, Tehran realizes that there will be “tremendous costs and consequences and implications” if they don’t comply.

“President Obama has made it very clear that we are going to prevent Iran from having that type of nuclear weapon that they – they were going on the track to obtain,” Brennan said. “So if they decide to go down that route, they know that they will do so at their peril.

"It's not a question of trusting the Iranians on this, and I know that Secretary Kerry and President Obama are comfortable with what it is that we are insisting on, as far as that verification regime.”

Fox's Chris Wallace noted that the US's “track record is not good” regarding Iran's nuclear weapons program, and that Iran “fooled us repeatedly,” with regard to facilities at Arak, Natanz and Fordow.

"We've gone to school on some of those developments over the last decade or so so that we can now verify have a better plan and opportunity to verify some of the things they say that they're going to do and not do,” Brennan said.

He called reports of an additional secret nuclear site "speculation and rumor” and expressed confidence that the US is aware of all of Iran's nuclear sites.

Asked about the danger of a nuclear arms race, Brennan said: “We've talked with our Gulf partners... and I believe that they do have confidence that the United States is going to be sort of the security guarantor in that region to prevent this type of escalation that's going to include nuclear weapons.”