According to F. William Engdahl at Global Research the US might have something to do with the Uygur riots in Xinjiang. He points to NED funding of the main Uygur organizations in the US. I find his arguments a bit weak: it concerns 200,000 dollar. But Global Research has a good reputation so it is certainly worth paying attention to.
But what to think of the riots? China traditionally has relied on assimilating its minorities. In places like Urumqi, where the Chinese have the majority that seems to work reasonably well. But in the south-west of Xinjiang where there are few Chinese (and no oil to seduce them to come) that doesn't work. It were people from the south-west who made the riots. But even when assimilation works there is discrimination. All the good jobs go to the Chinese and Chinese employers don't want to do anything with Uygurs who they often see as terrorists. A final factor is the scripture. You have to learn Chinese scripture from your childhood - otherwise you will never really learn it and you very easily forget it characters. This means that the Uygurs are functionally illiterate for Chinese society and are condemned to jobs that require little or no literacy. China has tried to remedy this by introducing a law in 2002 that forces the Uygur to have education in Chinese. Obviously that will generate its own problems - specially for the Uygurs in remote regions who can't pick up some Chinese words on the streets. It doesn't help either that China is nervous about religion.
I would like it if the Chinese gave the Uygurs and Tibetans their freedom. But - given the minerals, oil and national pride involved - am pessimistic about that. Assimilating those people - as China's government wants - will be a hard struggle.
Since 2002 China has introduced that Uygur children will be educated in Chinese. It will help with the language, but on other fronts it may work alienating.
With massive immigration China is trying to make the Uygurs and Tibetans minorities in their own area. It may work for China in the short run. But on the long run it may hurt China just as the fate of the Indians keeps damaging the reputation of the US.
Some newspapers talk about the Xinjiang as if it would endanger the unity of China. I don't believe so. 10 million Uygurs and 5 Million Tibetans are nothing in a country of 1.3 Billion. When China has fallen apart in the past it was always because the central government was weak and provincial rulers made themselves (semi-)independent. Ethnic divisions didn't play a role in that. China does have have different ethnic groups and languages among the Han Chinese and that has occassionally led to war, but those occasions were rare.
Postscript 1: The NY Times has an article about Chinese immigrants in Xinjiang. They live in a kind of army city that has also defense purposes.