Selective Availability
During Desert Storm the Pentagon deliberately degrades the civilian GPS signal worldwide — Selective Availability — so that any adversary navigating with off-the-shelf receivers wanders by an order of magnitude.
A working catalogue entry, kept current. Each paragraph is drawn from the publicly documented record.
During Desert Storm the United States deliberately operates Selective Availability — the random degradation of the civilian GPS signal — to deny the same accuracy to Iraqi forces using off-the-shelf receivers. Coalition troops with military receivers see metres; civilian users see hundreds of metres.
The episode demonstrates that GPS is not a single signal but two: one for those Washington trusts, one for everyone else. The two-tier architecture remains baked into the system to this day, and is the explicit reason every other major power has built its own.
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