Don't forget that the Chinese hacked the personnel records of federal civil service -- active and retired, plus the military personnel records -- active and retired during the Obama years. Obama did nothing. Its believed the Chinese could sift thru those to determine agents. Then, trace those who entered China or contacted Chinese outside China.
The CIA was able to identify the addresses on the hackers in Beijing. No doubt, the NSA and National Geo-Spatial Intelligence Agency provided those.