Also see the history of "window" (chaff) in World War II. R&D people for both the Allies and the Germans realised, as improvements of the new "radar" continued, that radar doesn't see a difference between an aeroplane and a suitably sized radio-reflecting object, say a strip of foil. So, if you chuck a bunch of these foil strips out of a plane, now the enemy radar is full of "planes" that don't really exist.
Both sides stalled deployment of this trivial yet effective countermeasure because they believed once they used it their opponents would immediately understand how it was done ("Gee, immediately after the German bombers did that trick which messed up our radar we found loads of metal strips in trees all over the area they attacked...") and so copy it - and both had "official" estimates made which said their opponents would surely benefit more than they would once it came into use.
Both sides stalled deployment of this trivial yet effective countermeasure because they believed once they used it their opponents would immediately understand how it was done ("Gee, immediately after the German bombers did that trick which messed up our radar we found loads of metal strips in trees all over the area they attacked...") and so copy it - and both had "official" estimates made which said their opponents would surely benefit more than they would once it came into use.