Indeed, ever since the 1972 Munich Olympics when a group of Palestinian commandos calling themselves "Black September' stormed the athlete's village taking a number of Israeli athletes hostage and later killing 11 athletes and coaches, the specter of terrorism has haunted every Olympics since.

With thousands of international journalists currently in the country covering the Games, the little known Uyghur insurgency, which first began in 1990, may well be tempted to drum up instant publicity for their cause, as they did on Aug. 4 – just four days before the opening session – by attacking a customs post.

On Monday, in the Xinjiang border city of Kashgar, two men crashed a dump truck into a group of police officers before throwing five homemade explosive devices into their barracks. Sixteen policemen were killed and 16 injured. Chinese authorities, suspecting a terrorist plot arrested both attackers and identified them as two Uygur men, ages 28 and 33.

Chinese authorities moved quickly to reassure the public as well as athletes and visitors that the Games would be safe after China's deadliest terrorist attack in more than a decade.

"The attack came as athletes continued to arrive in Beijing ahead of Friday's opening ceremony to launch the Olympic Games, which are being seen as a pivotal symbolic moment for China after three decades of dramatic economic reforms," says the Asia-Pacific foundation.

"The recent attack in Kashgar was timed to maximize publicity. It was a very clear statement of intent to launch an attack just a few days before the Olympics begin, and where the Uyghur insurgency first began," said the London-based Asia-Pacific Foundation, a think tank that specializes in terrorism affairs.

"It carries enormous symbolic significance," said MJ Gohel and Sajjan Gohel.

However, the two analysts think it is unlikely that any Uyghur group will be able to attack Olympic venues, spectators or athletes directly, given the intense security in Beijing. What does worry the authorities is that attacks could take place in other major cities like Shanghai, Yunnan, Tianjin and Shenyang which will host some of the football (soccer) matches during the Olympics. Another concern is that China's embassies and cultural centers could also be targeted in the West to take the spotlight away from the Olympics.

The Xinjiang Uyghur Autonomous Region lies in China's northwest, bordering central Asia. Covering a sixth of the country's total territory, it is a vast mineral-rich but sparsely populated region with around 19 million inhabitants. Around 8 million are Turkic-speaking Uyghur Muslims, concentrated in the south of the region around cities such as Kashgar, known to the Chinese as Kashi, which lies around 2,500 miles from Beijing

Chinese state security believes that the terrorist group, East Turkestan Islamic Movement (ETIM) were behind the attack on the police. In a recent video, entitled ""Our Blessed Jihad in Yunnan," three men who said they represented the little-known Turkestan Islamic Party (TIP) threatened to attack the Olympics and claimed responsibility for recent bus blasts in Shanghai and Yunnan. However, Beijing doubts their involvement in those incidents.

The Asia-Pacific Foundation experts believe that "in reality the ETIM and TIP are one and the same." In 2002, the ETIM has been deemed a terrorist group by the United Nations and the United States.

In Xinjiang, an extra layer of security screening has been added to 13 airports. Certain liquids, including alcohol, are banned from trains there, and a security inspector has been put on board each of the 4,000 buses in Urumqi, the region's capital.

In Beijing, more than 100,000 military personnel, 74 airplanes and 47 helicopters have been deployed to ensure security. In addition, the government would put up to 6,000 security people on Beijing's 18,000 buses during the Olympics, and another 30,000 at bus stops and terminals. The Chinese government has also been installing tens of thousands of surveillance cameras on lamp poles and in Internet cafes and bars.

Western companies like IBM, General Electric, Honeywell and United Technologies have been shipping their latest computer tools to automatically analyze video images from thousands of cameras and alert computer operators to patterns that might indicate a threat.

Indeed, the Beijing 2008 Olympics might well be the most security conscious Games ever organized.