Three Americans imprisoned by Tehran could be set free if the U.S. releases the Iranians it has behind bars, President Hassan Rouhani suggested on Sunday.

“If the Americans take the appropriate steps and set them free, certainly the right environment will be open and the right circumstances will be created for us to do everything within our power and our purview to bring about the swiftest freedom for the Americans held in Iran as well,” Rouhani told CNN.

Iran is holding at least three U.S. citizens: Washington Post journalist Jason Rezaian, former U.S. Marine Amir Hekmati and Christian pastor Saeed Abedini. Rezaian and Hekmati have been charged with spying while Abedini has been detained since 2012 for hosting Christian gatherings.

A fourth American, Robert Levinson, disappeared in the country in 2007, but his current condition – nevermind location – is unknown.

“If the Americans take the appropriate actions vis-à-vis Iranian citizens who are being imprisoned here, then the right atmosphere and environment will be created for reciprocal actions, perhaps”

- Hassan Rouhani

The U.S. has 19 Iranian citizens in prison, all on charges related to sanctions against Iran’s nuclear program.

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“There are a number of Iranians in the United States who are imprisoned, who went to prison as a result of activities related to the nuclear industry in Iran,” Rouhani said Sunday through an interpreter. “Once these sanctions have been lifted, why keep those folks in American prisons? So they must be freed.”

Rouhani, who is in New York for the UN General Assembly, seemingly suggested a quid-pro-quo could be arranged if Iran had its prisoners released.

“If the Americans take the appropriate actions vis-à-vis Iranian citizens who are being imprisoned here, then the right atmosphere and environment will be created for reciprocal actions, perhaps,” he said.

Rouhani added that “nothing would make me happier” than to help someone in prison, echoing comments he made to journalists, including representatives from the Washington Post, earlier this weekend.

“It is important to me to find a way, if there is a way, to set them free quicker,” Rouhani said Friday. “I wish to set as many people free as possible.”

Rouhani said Friday he didn’t want to use the word “exchange” but he could envision finding ways to “move the legal files forward” in Iran and that he had “suggestions and various legal actions” to use as leverage to that end.