Two Iranian AIDS physicians—brothers Arash and Kamiar Alaei, MD—were convicted for allegedly participating in a U.S.-backed attempt to overthrow the country’s Islamic government, The Associated Press reports. Their arrest is the latest in President Mahmoud Ahmadinejad’s crusade against Iranians with Western connections, whom he perceives as a political threat.

“They aimed at creating social crisis, street demonstrations and ethnic disputes,” the general director of the Intelligence Ministry’s counterespionage section said, according to the state-run IRNA news agency. Two other unnamed Iranians were also arrested and sentenced in this case.

The brothers were arrested in June; they were tried in a one-day, closed-court session in December. The length of their sentence has not yet been made public.

The Alaeis ran a clinic in Tehran and operated HIV treatment and testing programs directed toward at-risk populations such as sex workers and intravenous drug users. They also held HIV/AIDS training courses for Afghan and Tajik health care workers.

“We don’t know why they were targeted. Most of their presentations were about innovative work in Iran on HIV prevention. If anything, Iran should have been excited that something positive like this was coming from Iran,” said Sarah Kolloch of the Massachusetts-based Physicians for Human Rights.