I'm playing the unmodded European version of the game, and I suspect the mission "Top Secret" is either bugged or made it into the game in an unfinished state.
I've successfully taken over the base and captured the documents. At this point, the game suggests that I can return them to Lond (but it's probably a bad idea), or give them to someone else. And sure enough, Puerto Viejo seems to be enjoying quite an influx of tourists when I arrive.
Who else can I give the documents to? I've already tried Sosa's administration in Artrigo (barring Sosa himself, who won't talk to me at this point), Tanya's rebels in their camp, and Emilio Calderon: no-one has a dialogue option regarding it.