Unclear wording. Does moving "forward" mean to do something earlier than planned? Were we supposed to expect some other publication date when told that "the material was obtained a week before the attempted coup"?
To answer your question:
Wikileaks moved the publication to an earlier date. They apparently wanted to release it later (probably to prepare better), but thought it was relevant because of the coup attempt.
Regarding clarity, I avoid using "forward" and "backward" with regards to time.
That came out wrong. I don't avoid talking about a forward and a backward direction of time. What I avoid is saying that a planned event has been moved forward or backward, because people have different ideas of which means which.
This would be considered clear wording by proficient English speakers, 'However' sets up the clause, and 'has moved forward its publication schedule in response to..' is pretty self explanatory.
Generally one does not need to write "Wikileaks had publication of the material planned for a later date than today." -- "has moved forward" implies the former.
I think it requires the reader to perform an unfortunate extra step or two of inference. It seems preferable, in my humble opinion, to avoid this in situations where you want to be sure that you are expressing yourself unambiguously.
Yes, conventionally, in English (well, at least, American English, and I've seen it frequently enough in British English usage that it seems to be the same there, but its at least possible that its not universal), "moving forward" the time of a planned event means moving it earlier in time, while "moving back" the time of a planned event means moving it later in time.
"Forward/back" here is similar to closer/farther from the head of queue.
I do agree that the answer could have been worded more clearly.