While counter-terrorism is mainly the responsibility of the police and paramilitary People's Armed Police, the military plays an especially influential role in Xinjiang. Military units there operate as de facto governments over certain cities and vast amounts of farmland and mining operations, maintaining their own police and courts.
Bordering on Pakistan, Afghanistan and several unstable Central Asian states, Xinjiang is prone to unrest and violence blamed on radicals among the Uighur population who have been waging a low-intensity insurgency against the Chinese government for decades.
While Beijing has released little information about the Beijing attack the first in the Chinese capital in years it follows a string of violent incidents in Xinjiang this year.
Uighur activists say economic marginalization and cultural and religious restrictions are fueling the violence, while Beijing blames overseas-based instigators.