The United States is confident it can prevent Iran from developing nuclear weapons even if the Islamic republic pulls out of talks.

The United States is confident it can prevent Iran from developing nuclear weapons even if the Islamic republic pulls out of talks, CIA Director John Brennan said in remarks broadcast Sunday.

Speaking on Fox News Sunday, Brennan said America has multiple measures at its disposal to ensure Iran doesn't become a nuclear power.

"There are a number of things that the United States has available to it to prevent Iran from getting a bomb," the director of the Central Intelligence Agency said.

Iran and six world powers are in negotiations to clinch a landmark deal that would have the country scale back its disputed nuclear program in return for relief from sanctions.

"President Obama has made it very clear that we are going to prevent Iran from having that type of nuclear weapon that they were ... going on the track to obtain," Brennan added.

"So, if they decide to go down that route, they know that they will do so at their peril."

Asked about reports of an underground nuclear site near Tehran, Brennan said: "I am confident that we have a good understanding of what the Iranian nuclear program entails."