A lawyer representing one of the four U.S. citizens jailed by Iran told Reuters on Thursday that the four had been released from Tehran’s Evin prison and were now under house detention. He expressed his optimism that this was a first step toward their eventual departure from the Islamic Republic.

Businessmen Siamak Namazi, 51, and Emad Shargi, 58, as well as environmentalist Morad Tahbaz, 67, who is also of British nationality, are among the Iranian Americans, according to Jared Genser, an attorney who represents Namazi. The identity of the fourth American has not been revealed.

“The move by Iran of the American hostages from Evin Prison to an expected house arrest is an important development,” Genser said in a statement. “While I hope this will be the first step to their ultimate release, this is at best the beginning of the end and nothing more …. There are simply no guarantees about what happens from here.”

Freeing the four would remove a major irritant between the United States and Iran, though the nations remain at odds on issues from the Iranian nuclear program to Tehran’s support for Shi’ite militias in nations such as Iraq and Lebanon.

Namazi, who in 2016 was convicted of espionage-related charges the United States has rejected as baseless, has been detained by Iran for more than seven years. His father, Baquer, was allowed to leave Iran in October for medical treatment after being detained on similar charges also rejected by Washington.

Tahbaz was arrested in 2018 and sentenced to 10 years in prison for “assembly and collusion against Iran’s national security” and working for the United States as a spy. Shargi was convicted of espionage in 2020 and also sentenced to 10 years.