James Bamford discusses this at length in The Puzzle Palace - https://en.wikipedia.org/wiki/The_Puzzle_Palace
http://en.wikipedia.org/wiki/Daniel_Ellsberg#Fielding_break-...
The article quotes an employee of the law firm clearly stating he doesn't suspect the state department was involved. It also reports that the state department has repeatedly denied any involvement. Neither the headline nor any part of the article declares that the government was involved in the breakin.
/s
Why? Are you new here? Want to read some transcripts of Nixon ordering all kinds of shady things along a similar vein? http://law2.umkc.edu/faculty/projects/ftrials/ellsberg/nixon...
That said, it could just as easily be foreign intelligence operatives looking for material with which to extort US spies/diplomats.
After assessing the surveillance footage, Schulman said he believed the motivations were likely political, but did not suspect department involvement. "It wasn't professional enough," he said. "It is possible that an Obama or Hillary supporter feels that I am unfairly going after them. And the timing of this is right after several weeks of very public media attention so it seems to me most likely that the information sought is related to that case. I don't know for sure and I want the police to do their work."
Chances are, it was.
Just look for the agency with the most interest in their documents.
Do you have a better hypothesis?
Maybe it would have been done by a group interested in having it look like the government was trying to steal data relating to this whistleblower case? Even weirder things than that have happened IRL.