An unusually detailed 60-page study, to be released Tuesday by Mandiant, an American computer security firm, tracks for the first time individual members of the most sophisticated of the Chinese hacking groups — known to many of its victims in the United States as “Comment Crew” or “Shanghai Group” — to the doorstep of the military unit’s headquarters. The firm was not able to place the hackers inside the 12-story building, but makes a case there is no other plausible explanation for why so many attacks come out of one comparatively small area.

Officially part of the Chinese army or a renegade group?

It's very fluid... most certainly a bit of both. 

all paid for, at least, by the Army.  

More here:

http://pandawhale.com/post/17060/chinas-army-is-seen-as-tied-to-hacking-against-us-nytimescom

It's really hard to not see this as an act of war.