China 10,000-km range nuclear missile DF-31A drills.
The DF-31A intercontinental ballistic missile (Western designation CSS-10 Mod 2) is an improved version of the original DF-31 (CSS-10 Mod 0).
It was adopted in 2007. Currently the DF-31A is in service with Second Artillery Corps, that are de facto strategic missile forces of Chinese army.
It was estimated that by 2009 approximately 30 DF-31 and DF-31A missiles were in operational service.
Most likely that the number of operational DF-31A missiles has increased since then.