Below is an article published by The New York Times:

The United States ambassador to China made a recent visit to a mountainous region of western China, where dozens of Tibetans disaffected with Chinese rule have set themselves on fire. The visit occurred in late September, and the ambassador confirmed it publicly on Wednesday.

The ambassador, Gary F. Locke, visited two Tibetan monasteries on Sept. 26 as part of a trip to western China. The monasteries, which have not been involved in the 55 self-immolations across the Tibetan plateau since 2009, are in Aba Prefecture of Sichuan Province, the area where almost two-thirds of the Tibetans who have set themselves on fire lived.

It was Mr. Locke’s first trip as ambassador to a part of China where most of the people are ethnic Tibetans.

Much of the Tibetan plateau has been roiled by protests against ethnic Han rule since 2008, when an uprising spread from Lhasa, the Tibetan capital, to eastern Tibet, which lies in the Chinese provinces of Sichuan and Qinghai.

“I went to Aba Prefecture to see it for myself,” Mr. Locke said in a brief statement in response to questions from The New York Times. “I was struck by the unique Tibetan culture and met many ethnic Tibetans to learn more about how they live and work, such as an 88-year-old monk at one of the monasteries I visited. Ethnic diversity adds richness to a society.”

He continued, “I hope others will make the same visit.”

The Chinese Foreign Ministry had no immediate comment on the trip. Tibet is a particularly delicate issue between the United States and China, which labels Tibet a “core interest” and has admonished American presidents who have met with the Dalai Lama, the exiled Tibetan spiritual leader.

The publicity around Mr. Locke’s visit could be seen by China as a sign of further foreign interference in what it considers a domestic matter.

But an embassy spokesman said Wednesday that the trip to Aba was not made in secret and was known by Chinese officials. Before going there, Mr. Locke, whose activities are of great interest to Chinese citizens because he is Chinese-American, had spent time meeting officials and business leaders in Chongqing and Chengdu.

The two monasteries that Mr. Locke visited were in Songpan, an area about 100 miles east of the town of Aba, which is called Ngaba by Tibetans and has been the epicenter of the self-immolations. The first self-immolation by a Tibetan monk in modern history took place in 2009 in Aba. The monk was from the Kirti Monastery, where Chinese security forces have been clamping down since officers killed some civilians in Aba during a 2008 protest. The second monk to set himself on fire, in March 2011, was also from Kirti.

A security cordon has generally kept foreigners out of the town of Aba, and the Chinese government has restricted access to many other parts of the Tibetan plateau. Foreigners, however, have had some access to Songpan, where horse-trekking is popular among tourists.

Word of Mr. Locke’s trip to Aba first emerged on Monday, when The Times obtained a photograph of the ambassador greeting the 88-year-old Tibetan monk. A reporter posted the photograph on Twitter, but the embassy had no immediate comment. After being asked about the trip at a daily news briefing in Washington on Tuesday, a State Department spokeswoman acknowledged that Mr. Locke had visited Aba.

“When he was in Aba, he met with a number of local residents, including ethnic Tibetans,” said the spokeswoman, Victoria Nuland. “You saw the quite poignant photo. Some of them work in the travel industry. He also visited villages and monasteries to learn more about how ethnic Tibetan people live and work, and to have a chance to talk to them.” Ms. Nuland added, “We have grave concerns about self-immolations in Tibet and about the underlying grievances that the Tibetan people have.”

Mr. Locke released his statement the day after the briefing. Robert J. Barnett, a scholar of Tibet at Columbia, said the visit “suggests the embassy is finding creative ways to communicate messages within China that are effective without being aggressive.”

In the photograph, Mr. Locke, in a gray suit, is bending down to shake hands with the monk, who is seated, and Mr. Barnett said Chinese would understand the symbolism — an “indication of respect toward religion, the elderly and Tibetan culture.”