What is kh?

Some articles on kh:

List Of Titan Launches - Launches - 1977
... OPS-3151 (DSP) 13 March 1841 Titan III(24)B 24B-19 3B-54 VAFB SLC-4W LEO Successful OPS-4915 (KH-8A) 12 May 1426 Titan III(23)C 23C-14 3C-32 CCAFS LC-40 GSO Successful OPS-9437 (DSCS-II) OPS ...