The six-minute video, issued two days before the Beijing games open, was purportedly made by the Turkistan Islamic Party, which seeks independence for China's western Xinjiang region, the SITE Intelligence Group said. The militants are believed to be based across the border in Pakistan, where security experts say core members have received training from al-Qaeda.
"Choose your side," says the speaker, grasping a rifle and dressed in a black turban and camouflage with his face masked. "Do not stay on the same bus, on the same train, on the same plane, in the same buildings, or any place the Chinese are," he warns Muslims, according to SITE.
The Washington-based IntelCenter, another agency that monitors militant groups, identified the speaker as Abdullah Mansour from the group's religious education department. He speaks in the Turkic language of the Uighurs, a Muslim minority with a population of about 8 million in Xinjiang.
Last month, the group issued videotaped threats and claimed responsibility for a series of bus bombings in China in recent months. The latest video features graphics similar to ones used earlier: a burning Olympics logo and an explosion imposed over an apparent Olympic venue.
The latest video claims the communist regime's alleged mistreatment of Muslims justifies holy war. It accuses China of forcing Muslims into atheism by capturing and killing Islamic teachers and destroying Islamic schools, according to the SITE. It says China's birth control program has forced abortions on Muslim women.
"I think what they're doing is they're trying to capitalize on the buildup to the games," said Ben Venzke of IntelCenter.
More than 100,000 soldiers and police were guarding Beijing and other Olympic co-host cities. Terrorism experts say the heavy security presence would likely force attackers to target less-protected areas.
"I think the actual Olympics themselves, the venues, the guests, the athletes, are going to be safe," said Drew Thompson, director of China studies at the Nixon Center in Washington. "I would not be an alarmist."
Thompson added that Uighur groups haven't demonstrated they have the capacity to attack Beijing or other host cities during the games.
On Monday, assailants killed 16 border police and wounded 16 others in the Xinjiang city of Kashgar when they rammed a stolen truck into the group before tossing homemade bombs and stabbing them. Chinese authorities called the raid a terrorist attack and said they had arrested two men who are Uighurs.
Authorities have called the men terrorists, but officials have released no evidence linking them to a specific group.
Xinjiang's capital, Urumqi, appeared to be on high alert Thursday, the day before the games' opening ceremony in Beijing, thousand of miles (kilometers) away. Security guards were checking bags at the entrances of hotels, department stores and discos in the busy city, where office towers and apartments blocks have been shooting up in recent years.
Guards with red arm bands rode on most public buses, watchful for potential bombers. Small groups of police patrolled the sidewalks of the bustling Muslim quarter, where merchants cooked lamb kebabs and sliced up watermelons at fruit stands.
The officers were largely ignored by the Uighur women in colorful headscarves and the men wearing skull caps decorated with elaborate embroidery or sequins, who haggled over goods or shouted into mobile phones.
Meanwhile, in Kashgar - an hour and half west of Urumqi by plane - the police killed in Monday's attack were declared to be "revolutionary martyrs" during a memorial ceremony, the state-run Xinhua News Agency reported.
"The people of all ethnic groups in Kashi will remember you forever," said one banner held up by the crowd, Xinhua said, using the Chinese name for the town.
Although signs and slogans around the city urge people to "build a harmonious Kashgar," mutual resentment and contempt between the Uighurs and Han Chinese is almost palpable.
At the Hua Du Hotel, a help-wanted poster pasted near the front entrance said the business wanted to hire workers who were female and Han Chinese - the nation's majority ethnic group.
The manager, who wouldn't give her name, said, "We need someone with good language skills and most Uighurs can't speak Chinese well. We also have high standards for cleaning the rooms, and Uighurs just can't meet those standards."
In Kashgar's bustling Old City district, a 22-year-old Uighur shopkeeper said that Xinjiang independence was virtually impossible. The man, who only gave his English name Michael because he feared reprisals, said he opposed violent attacks on Han Chinese.
But he added, "I don't like the Chinese because they don't like Uighurs. We are Muslims and they dislike Islam. We have different values. We're two different people."
