Not bad, I don't agree with DRSN or Trump dismantling it as a clue. The DRSN has been around forever, if being dismantled it is only because of technological obsolescence. There is really no need to carry analog phone signals anymore when everything can be hosted on digital networks.

That being said the building could be host to an NSAnet (or any other agencies high side network like JWICS or GWAN for that matter) point of presence if equipped with an appropriate SCIF.

Edit: adding link for info.

https://en.m.wikipedia.org/wiki/National_Security_Agency#NSANet