ABA, China – The monk reached into the folds of his red robe, pulled out a small notebook, and gently slipped from its pages a tiny photograph.

The man in the creased picture was a relative. He used to be a fellow monk at the monastery perched in snow-wrapped mountains outside the town of Aba. Then a Chinese security officer killed him, the monk said.

It is a sorrow that cannot be spoken of in public. A local government "working team" visits the monastery often, looking for signs of discontent, according to monks there. Sometimes, they said, when returning to their living quarters from chanting or studying, the monks find a door busted in and possessions scattered after a search.

The monk showed the snapshot as a way of explaining why ethnic Tibetans, mostly current or former Buddhist clergy, are setting themselves on fire in Aba and surrounding regions in an unprecedented show of protest against Chinese rule. Since March 2011, between 20 and 24 have committed self-immolations, according to rights groups. Of those, at least 13 are said to have died.

"China in our eyes is not fair or peaceful," said the monk, a man in his early 40s who, like every ethnic Tibetan interviewed for this story, did so on the condition that he not be named and that certain details be withheld, for fear of getting dragged off by police. "We are suffering a lot in our hearts, and when we can no longer bear it we burn ourselves to death."

The Chinese government and its media have confirmed some of the self-immolations and denied others. But the government also goes to extensive lengths to prevent outsiders from visiting this area.

Police routinely block roads, search vehicles and turn back foreigners, especially journalists.

A McClatchy Newspapers reporter last week became the first from an American news organization to make it to Aba since the chain of self-immolations began. To do so, he hid on the rear floor of a vehicle under two backpacks and a sleeping bag as it passed through checkpoints.

Beijing has long blamed unrest in ethnic Tibetan areas on conspiracies hatched by the Dalai Lama, the Tibetan spiritual leader who fled to India after a failed uprising against Chinese rule in 1959.

But conversations with ethnic Tibetans in Aba and elsewhere in Sichuan province, where almost all of the self-immolations have occurred, suggest that China's authoritarian policies designed to tamp down disorder are fueling the troubles.

As the nation's vice president and presumptive next leader, Xi Jinping, tours the United States this week amid talk of greater understanding, his government at home continues to flood a wide swath of ethnic Tibetan lands with armed troops.

Sections of the town famous for its Tibetan Buddhist monasteries have come to resemble an armed camp. A few blocks from the entrance, paramilitary police stood behind riot gates with shotguns and assault rifles.

The security was so dense that it was impossible to speak with clergy or, indeed, anyone in Aba because of the risk of bringing danger to those interviewed.

Aba, in the high mountains and mist, gained international attention as an epicenter of Tibetan turmoil last March when a monk from the Kirti monastery lit himself ablaze. He was reportedly commemorating the third anniversary of 2008 demonstrations and riots across the Tibetan Plateau, including Aba, which ended in bloodshed.

After that self-immolation, some 300 other monks were allegedly hauled away from Kirti in trucks, sparking concern from the United Nations.

Chinese officials point out that they have spent billions of dollars constructing hospitals, roads and schools in Tibet, which is referred to by Beijing as an autonomous region, and nearby areas like those in Sichuan.

Or as a billboard depicting green fields and blue waters outside Maierma Township, approximately 20 miles from Aba, puts it: "Building a civilized, new Aba together."

Many ethnic Tibetans recognize the benefits of the government's projects. But they chafe at the government's restrictions on free expression of their culture and religious practices, and they speak of anguish over being separated from the Dalai Lama.

"If you say the government is not treating us well, that's not completely true, they are providing us with good things," said a 26-year-old trader in Hongyuan, which sits 65 miles or more to the east of Aba. "But on the other side, the police are behaving badly. We don't know what to say about the situation."

His younger brother spoke up: "Of course things are not good, they are killing people."

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