"Mapping the domain" is one thing all military agencies try to do, just like if you were a hacker who gained access to an unfamiliar subnet you'd likely try to figure out the lay of the land.

I'm more surprised that NSA didn't already have programs to map the Internet, given how long nmap has been around.

However it has the key words N, S, and A so let's just assume it's something sinister and evil.