Reports indicate major violence erupting in western China this week, with knife-wielding assailants attacking two towns.

Casualties are said to involve dozens of Uighurs and ethnic Han (the largest ethnic group in China), as well as extensive property destruction. The attacks were apparently aimed at local police forces, with dozens of police cars damaged.

The incident seems to represent an acceleration in violent relations between the mostly Muslim Uighurs and the government. In 2013, a car filled with gasoline drove over people in Tiananmen Square before exploding at the entrance to the Forbidden City. The attack killed two bystanders and injured another 40. Earlier this past March, 29 people were killed at Kunming train station in Yunnan province (in China’s south) by knife-wielding assailants with, according to Chinese authorities, connections to the Uighur community. This was followed by a train station bombing and an attack on a marketplace, both in Xinjiang. The latter killed over 30 after two cars drove into the marketplace crowd, the passengers reportedly flinging explosives out the window. In May, a Xinjiang police station was car bombed.

A growing crackdown by the Chinese central authorities on Muslims is now underway, perhaps in reaction to these incidents. Chinese officials this year sought to discourage observance of Ramadan, one of the “five pillars of Islam.” Chinese authorities reportedly forced Muslim students and government employees to break their fast during Ramadan. (Muslims are expected to fast during the day for the month-long Ramadan period.) This week’s incident may have been a backlash to the central government’s increasing pressure.

The Chinese situation is not the same as the one confronting Moscow at the end of the Soviet Union. Whereas non-Slavic minorities were a growing percentage of the Soviet population, there is little prospect, at this point, of the Han losing their ethnic dominance over China. The Beijing authorities, in turn, use the Han who have settled there (representing perhaps 40 percent of the population in Xinjiang), as well as a substantial military garrison, to maintain control over the restive “Autonomous Regions” of Xinjiang and Tibet.

But as China comes to rely more heavily on Russia and central Asia for energy, instability in Xinjiang will pose a growing threat. Railways and pipelines represent extensive, expensive infrastructure that can be very vulnerable to attack. Beijing may have hoped to limit vulnerability to foreign naval threats to its energy lifeline only to find itself threatened by religious and ethnic unrest.