YENGISHAHAR, China – Shortly after dawn on July 9, the local government here bused several thousand students and office workers into a public square and lined them up in front of a vocational school. As the spectators watched, witnesses said, three prisoners were brought out and killed by a firing squad.

The young men had been convicted of having connections to terrorist plots, which authorities said were part of a campaign aimed at disrupting the Beijing Olympics by the East Turkestan Islamic Movement, an underground separatist organization here in the vast Xinjiang region of western China. The group has long fought for independence on behalf of the region's Muslim Uighur inhabitants.

The public execution was a dramatic example of the massive, unforgiving security operation that China has mounted to protect the Beijing Games, which are three weeks away. Communist Party authorities say there is an urgent threat of violence and anti-government protest.

"Especially as the Beijing Olympic Games draw near, a range of anti-China forces and hostile forces are striving by any means and redoubling efforts to engage in troublemaking and sabotage," said Yang Huanning, a vice minister of public security and an anti-terrorism specialist, in a declaration to the Public Security Bureau's newspaper.

Precautions have proved so sweeping that some observers question whether the sense of fellowship and fun that is supposed to accompany the Olympics can survive. In addition to the crackdown here in Xinjiang, for instance, have come new visa restrictions, roadside checkpoints, reinforced pat-downs at airports and subway stations, and raids on bars popular among foreigners.

On Thursday, China issued a manual advising the public what to do in the case of a terrorist attack, according to state-run media. The manual explained how to respond to 39 scenarios including kidnappings, shootings and attacks involving chemical, biological and nuclear weapons.

The Beijing Public Security Bureau warned recently on its Web site that any demonstration must have prior approval from authorities, in effect banning anti-government protest.

Aware of the misgivings about overkill, Chinese authorities have said their top priorities must be to guarantee the safety of Olympic athletes and spectators and to prevent political protests from ruining the display of international harmony long promised to the Chinese people.

Ma Xin, a government security expert who is part of an Olympic advisory team, said security must be tight because thousands of foreign dignitaries will be on hand, including President Bush, and could become targets for international terrorist groups such as al-Qaeda.

In April, China all but stopped issuing multi-entry visas and began requiring tourists to submit documentation such as hotel reservations, plane tickets and other information.

Some human rights advocates, business associations and foreign visitors say the crackdown has more to do with keeping out potential foreign protesters upset about human rights issues. They say the process is alienating foreigners.

The Washington Post