H/T to DY Lu. China has quietly constructed a surface-to-air missile site in Dongfeng County (东丰县), Jiling Province since last year.
Based on its layout, the location is likely to be a new base for the Chinese HQ-9 long-range air defense missile system.
The location is just 140km away from the border with North Korea.
Thanks a lot. In this satelite image dated around the end of 2017, the new site construction was near complete, and HQ-9 had not yet deployed. We could reasonably estimage that HQ-9 might has been on-site for now.