Shortly after you pick-up the RLS-7 in the game, you cross a bridge (which overlooks a highway bridge where some enemy soldiers battle giant mutant spiders).

On the other side of this foot-bridge, use the TDM to revert the lockers in the room and reveal a note inside one of them.

The note is written in the familiar style of everyone's favorite cultural tour-guide from Kazakhstan (except perhaps, for the actual Kazakhstan).