In the 90s I remember critical media linking Sandagergård to the Echelon Project. There were also rumors about foreign contractors operating at the facility.
I've always thought about this when I was near Sandagergård (it's situated in a beautiful place off the beaten path not far from Copenhagen) but as far as I remember the stories where mostly based on speculation without any hard facts. With these recent disclosures it seems that there might have been some truth to those old stories.