WHEN PRESIDENT OBAMA spoke at a university in Burma during his brief visit to that Southeast Asian nation on Nov. 19, U Gambira was seated in the front row.

As a 28-year-old Buddhist monk, U Gambira had led nonviolent, pro-democracy protests in 2007. He was arrested, sentenced to 63 years in prison and tortured. His release this January was a telling step in the progress of Burma’s dictators toward democratic reform — progress that Mr. Obama has encouraged and that he was in part celebrating with his six-hour visit.

Now U Gambira is back in prison.

The 33-year-old’s rearrest Saturday is also a milestone — a reminder that the rule of law remains a distant prospect for the long-suffering nation. Western and Japanese officials who have been eager to claim Burma as a success story, end economic sanctions and move on should take note.

Like hundreds of political prisoners set free in the recent thaw, U Gambira was conditionally released, meaning that Burma’s generals could reimpose his multi-decade sentence on a whim. His arrest was ostensibly for an offense committed in February, when he tried to reenter his former monastery, since closed by officials. At the time, Buddhist officials loyal to the regime essentially defrocked him. Today he is a “former monk.”

“It is not clear why the authorities have decided to press charges against U Gambira more than nine months after the alleged offenses occurred,” Amnesty International said. The latest charges against him, according to Burma Campaign UK, include trespassing and “damaging the dignity of the country.”

U Gambira’s rearrest is not the only human rights violation to occur lately. A villagers’ protest against a copper mine was violently suppressed, and monks and others seeking to show support for the protesters have been jailed. Ethnic violence continues, by the army against the Kachins and, unpunished, by ethnic Burmese against Muslim Rohingya.

None of this means that the movement toward democracy is derailed. But the setbacks show how fragile and reversible the progress remains.

U Gambira’s persecution is particularly appalling. In prison in 2009, he was strapped to a chair for weeks at a time, force-fed and brutally beaten on the head. Since his release he has said his health has far from recovered, but doctors in Burma were afraid to treat him and officials would not allow him to leave the country.

The Obama administration has had nothing to say on this. When we inquired, a White House spokesman said officials are “monitoring reports that U Gambira has been detained” and “urge the government of Burma to be fully transparent and follow due process of law.”

But there is no rule of law in Burma. “Due process” could include ordering U Gambira to serve the remaining decades of his sentence. The needed message is simpler. Before the next high-ranking Burmese official is feted abroad, Burma’s new friends should insist on release and medical care for U Gambira and unconditional freedom for all political prisoners.