IN THE MINDS of China's leaders, Jiang Yanyong, the 72-year-old army surgeon who became a national hero for exposing the Chinese government's coverup of the SARS epidemic, could now be the single most dangerous individual to the country. Authorities have detained Dr. Jiang for more than a month since he wrote a letter to the government denouncing the 1989 Tiananmen Square massacre. As reported by The Post's Philip P. Pan, Chinese authorities have subjected Dr. Jiang to "brainwashing sessions," forcing him to sit through intensive indoctrination until he "changes his thinking" and "raises his level of understanding." Dr. Jiang has refused to capitulate.

Why do Chinese leaders consider Dr. Jiang so threatening? His exposure of the government's SARS coverup instantly gave him an immense national respect that the Chinese government cannot control or take away. The semi-retired surgeon has been praised as "an honest doctor" and "a famous surgeon of the nation" in national publications, which have highlighted Dr. Jiang as a hardworking and loyal public servant who continues to visit patients and perform surgeries at an army hospital in Beijing. He has had a distinguished career with the People's Liberation Army and as a member of the Communist Party. Even one senior military official told The Post that "99 percent of the people support him," and that "I consider him a man of honesty and courage."

China has had some success at discrediting pro-democracy and religious dissidents as counterrevolutionary rebels and zealots, but they will have a hard time damaging Dr. Jiang's reputation. For one, Dr. Jiang isn't calling for an end to the one-party system or for democratization but rather is arguing that the party stands to gain more support and legitimacy by disavowing the state-ordered massacre at Tiananmen Square. Second, and especially unfortunate for Beijing, is that Dr. Jiang fits the profile of an archetypal Chinese hero -- that of a conscientious scholarly official who puts himself on the line to tell the corrupt emperor the truth for the sake of the people and is ordered punished. If news leaks out about Dr. Jiang's detention, which China's state-controlled press has not reported, China's "honest doctor" is likely to become its most famous, and credible, dissident.

Dr. Jiang's detention clearly demonstrates that China's leaders are in no mood to progress toward political liberalization, as many hoped when a new generation of leaders under President Hu Jintao took power last year. Mr. Hu allowed a time -- however brief -- of openness that was critical to confront and contain SARS. But his leadership has been complicated by former president Jiang Zemin's refusal to let go of his enormous influence. The power struggle has created a policymaking dynamic favoring hard-line extremism as the politically "safe" direction. But it is the wrong one. Just ask the relatives of the hundreds of people who died of SARS in 11 countries because China did not face up to the crisis when it first broke out. As Dr. Jiang wrote to the Chinese leadership, "The claim that stability is of overriding importance can in fact cause even greater instability." China -- and the world -- should listen.