Well, from my understanding of "Operation Shady RAT", they found out which organizations/gov'ts were targeted by taking over/siezing one of the info-collection and zombie-controlling computers. Much of the speculation that it was China is based on the fact that the hackings targeted the US, Taiwan, Vietnam, South Korea, etc...
For all we know, it could be North Korea or the US doing it. The fact that the controlling computer indicates only those targets could be a frame in case they get caught. I wouldn't be surprised if there are more control computers targeting other sets of countries and organizations. I also wouldn't be surprised if China really is behind it.