It looks like the US government knew exactly who hacked Sony when it placed the blame squarely on North Korea. Apparently, the NSA and, perhaps the South Korean intelligence apparatus, had already hacked North Korea's network and had been tracking Sony hackers.
At least, this is what we are being lead to believe.
As a layman, I have a few questions as I am sure you do regarding this matter that are not specific to the Sony hack. For instance, how did the NSA managed to insert its codes into the hacking tools used by the North Koreans? And does this speak to the skill levels between those hackers and the NSA?
And lastly, what other tools are available to Western governments to continue to track and hack unfriendly governments? It's like the North Korea is doing its best to look for and scrub out programs and codes, those that had been used by the NSA as as well ones that have been detected.
The dilemma for me here about these types of news reports is that while it is important that the public be informed, to a certain degree, it could also undermine future intelligence operations as well.