Last year, the U.S. government changed the Global Positioning System to make civilian GPS signals as accurate as their military counterpart. (Aviation Week & Space Technology compared the difference to knowing that you're standing on a football field versus knowing which yard marker you're standing on.) Can Osama Bin Laden use the more accurate GPS signal to target U.S. military forces in Afghanistan?
Probably not. At the press conference that announced the improvement in civilian GPS, then-Assistant Defense Secretary Arthur Money said the change would have "minimal impact on national security" because the Department of Defense can negate GPS signals in a localized "threat area." For example, if the military negated GPS signals in the Balkans, it wouldn't affect civilian users in Berlin, Frankfurt, or Athens. The ability to regionally block GPS signals led the Clinton administration to lift the intentional degradation of civilian GPS signals. Money said GPS signals would not be negated "unless we're in a conflict somewhere where we need to protect U.S. forces and/or coalition forces."
The U.S. government says it has no intention of degrading the worldwide civilian signal ever again. There has been no change in that policy since Sept. 11.
Read this Encarta article to learn how GPS works.
Your Explanation Is as Good as Mine. Some readers were confused by yesterday's column about covert operations. If covert operations aren't "intended to influence United States political processes, public opinion, policies, or media," how can the Bush administration leak its plan to the New York Times? Explainer doesn't know, but he did have a covert discussion with his colleague Chatterbox, who covertly theorized that the leak indicates a (covert?) split in the White House between hawks and doves. One of those camps may want the U.S. aid to Afghanistan's Northern Alliance to be made public, for whatever reason. The Explainer-Chatterbox summit was covert, so please don't tell him that I told you about it.
Explainer thanks the Interagency GPS Executive Board Web site.