Given that the Chinese have an entire military division devoted to penetrating our military,indusrial, and governmental computer systems as outlined in “Unretricted Warfare” by Qiao Liang and Wang Xiangsui both of the PLA, I would say it’s probably the Chinese.
Aside from the mititary division the Chinese have set up entire companies to recruit hackers on a worldwide basis.

In adition the Soviets and the Chinese have recently concluded several mutual assistence pacts so I am sure some sharing is going on between the two, but probably very little.