Which GPS system was jammed? The US? Or russian system? IIRC, the chinese were putting up there own GPS system as well, but it was small, and primarily for their part of the world.
Back in the late 90's the GPS system had limited precision because the GPS originally had a military application, at least that's what they told me in my class on the PLGR (plugger) GPS system we used in the Army at the time. Then they allowed it to be commercialized and voila, a multi-billion dollar industry sprouted up around the .gov system. Just a fun fact you didn't ask for.
Branden