This is an intelligence mission, it's just one of the least sinister of all the intelligence missions that can be performed from space. We are performing those missions - just not on this launch.
Given that is is a modern radar and part of an array, my guess would be deep subsurface 3d spectroscopy using ground penetrating radar technology, similar to what is now used in mining - http://adrokgroup.com/ , then you know where the distribution of elements are down to several miles below the surface, which means you then know where all the nuclear material in the world is and can spot when it moves. Oh and as a bonus, you have a huge edge on mineral rights.
http://en.wikipedia.org/wiki/List_of_NRO_Launches
This is an intelligence mission, it's just one of the least sinister of all the intelligence missions that can be performed from space. We are performing those missions - just not on this launch.