This story is being covered by the Vietnamese and English language media in Viet Nam. The only difference is that the Vietnamese reports I’ve seen don’t include any satellite photos. This alleged Chinese surface-to-air missile base is just 20 km (12 miles) from the border.
Below are two photos. The first is from the linked VNExpress International article and the second is from Google Earth, which anyone with a computer or smartphone and Internet access can find using either the web version or the app.
Click on the photo or the link above to zoom in and see more detail. You can see a military runway in the upper left and what appear to be six (6) launchers in the circle in the upper right part of the construction site.
In case you’re interested, the distance from Ningming County in southwestern Guangxi to Hanoi, the capital of Viet Nam, is a mere 178 km (111 miles), hence the concern of the Vietnamese government.
Let’s hope that China is not flexing its military muscle within spitting distance of the Vietnamese border.
Shalom (שלום), MAA
An International Educator in Viet Nam 
If this is indeed a SAM base, this is probably what it’s for: “Biden’s message to Beijing: Don’t expect U.S. to ease up over South China Sea and Taiwan” https://www.japantimes.co.jp/news/2021/02/06/asia-pacific/biden-south-china-sea-taiwan/