The Chinese government has previously warned of the growing Muslim insurgency within its own borders, blaming the Uighurs for a number of terrorist attacks inside China. The Uighurs have resisted heavy-handed Chinese restrictions on their customs and religious practices, and have cited the government crackdowns on resistance as further signs of repression of their culture and faith.
Previous numbers had placed the numbers of Uighurs fighting with jihadist groups in Iraq and Syria at around 100, but their actual numbers are likely impossible to estimate at this point. A recently released video from the Islamic State shows Uighur fighters for the first time publicly proclaiming allegiance to ISIS.
The claim on behalf of the Syrian ambassador is likely an attempt to stoke Chinese fears of the capabilities of the growing Uighur insurgency in Xinjiang province, an area subject to Uighur terror attacks and associated government crackdowns through the use of paramilitary riot police. The Chinese have been eager to draw a connection between their internal Uighur insurgents and the global threat of ISIS as a way to justify their internal military and police operations against the Uighurs as ‘counter-terrorism.’