An attack Monday that Chinese authorities called the deadliest terrorist act in more than a decade focused an international spotlight on China's Muslim Uighur minority, who share with their Tibetan neighbors many of the same ethnic and economic grievances against Beijing's Communist leadership.
Authorities did not identify the perpetrators of the attack, which left 16 soldiers dead. But a Chinese security spokesmen attributed the strike to the Eastern Turkestan Islamic Movement, which Beijing has called the most serious threat to the Olympic Games that begin this week.
The movement is based among the nearly 10 million ethnic Uighurs in China's vast western Xinjiang province, a native Muslim Turkic people who have long resented Beijing's rule. An extremist Uighur group thought to be based in Pakistan's tribal border areas threatened in a videotape last month to target the Olympics.
According to China's official Xinhua news agency, two ethnic Uighurs rammed a dump truck into a group of paramilitary police officers performing their morning exercises at a border patrol station in the crossroads city of Kashgar.
After the truck hit an electrical pole, the two men tossed grenades at the group and "hacked at the policemen with knives," according to the Xinhua account. Fourteen guards were killed at the scene, and two more died en route to the hospital.
The ethnic Uighurs were able to attack despite a security crackdown by central authorities determined to head off protests and unrest in advance of the official opening of the Beijing Olympic Games on Friday.
"We are prepared to deal with any kind of security threat and we are confident we will have a safe and peaceful Olympic Games," Olympic organizing committee spokesman Sun Weide told reporters in Beijing.
State Department spokesman Gonzalo Gallegos said the U.S. government "strongly condemned" the attack, but that U.S. authorities had few details about the incident.
"We're saddened at the loss of life and injuries caused by the attack and extend our condolences to the victims and their families," Mr. Gallegos said.
Independent accounts of the incident were not available, as Chinese authorities have curtailed unauthorized press coverage from the region.
Xinjiang is far less prominent on the world stage than Tibet, lacking a Nobel Peace Prize-winning spokesman like the Dalai Lama or a global network of high-profile sympathizers.
But the province's Uighurs say they face many of the same hardships and restrictions imposed on Tibet.
Among them: historical disputes over how much control Beijing has exerted over the remote province; demographic tensions with Han Chinese, who have been encouraged to settle in the province; economic inequality, as some charge the migrant Chinese are given better jobs and government posts; and religious friction over the Uighurs' Muslim religion and ties to other Central Asian peoples.
While the world's press focused on Tibetan protests targeting the international Olympic torch relay this spring, Beijing officials have made public details of far more violent plots that they blame on Uighur militants.
Chinese security authorities say the East Turkestan Islamic Movement is the single biggest threat to the Olympic Games. Kurexi Maihesuti, vice chairman of the Xinjiang Uighur Autonomous Region, said last week that security officials broke up five Uighur terrorist groups in the first half of 2008, including one plot to blow up a Chinese airliner.
But human rights watchdog groups have accused Beijing of using the terrorist threat to "justify harsh repression of ethnic Uighurs, resulting in serious human rights violations," according to Amnesty International.
Uighurs "were the only known group in China to be sentenced and executed for political crimes such as 'separatist activities,'" the London-based group said in its 2008 annual report.
Rebiya Kadeer, head of the Washington-based Uighur American Association, was one of five Chinese dissidents who met with President Bush last week ahead of his trip to the Beijing Olympic Games - a visit that infuriated Chinese officials.
She has accused China of using security for the Olympic Games as an excuse to crack down in Xinjiang, saying the Beijing government had provided no hard proof of terrorist activity in the region.
"I respect the Chinese people's desire to hold the Olympic Games, but I lament the fact that the Chinese government is using the games themselves to intensify the persecution of the Uighur people," she said in a recent statement.