“Iran now has one of the best prison programmes for HIV in not just the region, but in the world,” exclaimed Hamid Setayesh, the UNAIDS coordinator for the country, in 2006. “They're passing out condoms and syringes in prisons. This is unbelievable. In the whole world, there aren't more than six or seven countries doing that.”

Perhaps just as unbelievable is the fact that two of the physicians who helped pioneer Iran's progressive AIDS-prevention programme are now behind bars themselves. Tehran's Revolutionary Court last week sentenced the brothers Kamiar and Arash Alaei to, respectively, three- and six-year jail terms in the city's notorious Evin prison on charges of being US stooges bent on fomenting a velvet revolution to overthrow the state (see page 517).

One of the acts that apparently attracted suspicion was the brothers' participation alongside US government officials in two US–Iranian health-diplomacy round tables held in the United States in 2006 and 2007. The meetings were run by the Aspen Institute, a non-governmental organization founded in 1950 to provide an impartial international forum on major policy issues. The chair of one of the sessions introduced it proudly as one of the “first formal dialogues for almost 25 years” between Iran and the United States.

Human-rights organizations who have examined the brothers' cases say that their detention, which began in June last year, and their convictions on 31 December in a closed trial lasting barely half a day, both fell far short of the minimum international legal norms for a fair and equitable procedure.

An especially puzzling aspect of the case is that Iran's president, Mahmoud Ahmadinejad, has publicly supported international collaboration in science. Speaking at Columbia University in New York in September 2007, Ahmadinejad described researchers as “shining torches who shed light in order to remove darkness and the ambiguities around us in guiding humanity out of ignorance and perplexity”, and he invited Columbia faculty members and students to work with their counterparts in Iran. “You're officially invited,” he said.

Such dialogue — 'smart power' — should be encouraged by all sides, because cooperation in the relatively apolitical areas of medicine and science keeps open rare avenues of back-channel diplomacy. Unfortunately, 'dumb power' is currently prevailing. The action of the Iranian judiciary in this case can have only a chilling effect on such activities, and there have been ill-considered moves elsewhere. Prime examples are the shortsighted visa policies being pursued by nations such as France, which unjustly discriminate against Iranian researchers (see Nature 456, 680–681; 2008), and the Bush administration's declaration that the United States is seeking regime change in Iran by supporting 'pro-democracy' elements there. Academics in Iran who desire reform, but by self-determination, say that such covert US policies have left them vulnerable to the same charges faced by the Alaei brothers. More smart power is needed all round.

President Ahmadinejad. Your country's HIV-prevention programme has won respect in the Muslim world and beyond. As you said at Columbia University, the open scientific and medical dialogue needed to progress in issues such as the fight against AIDS must be above the contemporary realpolitik of broader political issues. We urge you today to request the appropriate authorities to review the cases of Arash and Kamiar Alaei so that the truth may prevail.