The most important instrument of Chinese policy is to use the mechanism of the SCO to strengthen own positions in regional security.
Secondly, desire to see the region economically stable and prosperous. Astana's interest in this case is quite obvious. And China wants to be close to the stable source of raw material and financial resources on the border of western provinces of their own, as well as a rich sale market, is more than logical.
Given the fact that under its Constitution of the PRC shall strictly adhere to the interests of the Chinese people, including abroad, attempts to force action on such communities necessarily entail a serious complication of relations with China.