1999 July 5
On 1999 April 5, the following notice appeared on the NASA/GSFC Orbital Information Group (OIG) WWW page:
As the result of a joint request from USSPACECOM, NRO, Pentagon, and other sources some objects have been removed from the OIG systems. This request was approved by NASA HQ. These objects were removed because they were deemed to be "sensitive satellites".
These 'sensitive' satellites comprise all operational DOD satellites including GPS and DMSP satellites. Since there are no longer any element sets for these satellites available for release to the public, I am no longer able to provide them here and they have been removed from the current lists. I will continue to work to see what can be done to reverse this decision.
As of 1999 June 23, it appears that the Department of Defense has quietly reversed its position on limiting access to GPS element sets. However, there does not appear to be any change regarding DMSP element sets.