> However, WikiLeaks has moved forward its publication schedule in response to the government's post-coup purges.

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.