TEHRAN, Iran — An Iranian-American reporter who was trapped in Iran for months on suspicion of trying to stir up a revolution was allowed to leave the country yesterday and return to America.

Parnaz Azima was one of four Iranian-Americans charged with endangering national security, an accusation they denied.

The charges have added to tensions between America and Iran, already high over American accusations that Iran was seeking to develop a nuclear weapons and is fueling violence in Iraq. Iran denies both claims. But Iranian authorities may be aiming to defuse the crisis. Ms. Azima was the second of the for American citizens allowed to leave in recent weeks. “The Iranian government probably thinks it has gotten enough mileage out of their detention,” a specialist on Middle East policy at the Council on Foreign Relations, Ray Takeyh, said.

Ms. Azima “left Iran today and is on her way to the United States,” Sania Winter, a spokeswoman Radio Free Europe-Radio Liberty, told the Associated Press from Washington. She would not give further details. Unlike the other three Americans, Ms. Azima — who works for RFE-RL’s Farsi-language service Radio Farda — was not imprisoned, but authorities confiscated her passport when she arrived in the country in January on a family visit.

Ms. Azima’s lawyer in Tehran, Mohammad Hossein Aghassi, said the charges against her had not been dropped but that she was allowed to leave after posting bail of around $450,000 using the deed to her mother’s house.