Falklands: CIA National Photographic Interpretation Center signal ("Increased Defensive Measures Port Stanley Area") [satellite intelligence] [declassified 2010]

The CIA's document release programme is explained here. The US Government had no satellite over the South Atlantic at the beginning of the conflict and took time to reposition one. Observation conditions were far from perfect: it was winter in the southern hemisphere. Accordingly this analysis may relate to one of the earliest if not the first sets of satellite photos.