AP, via, Yahoo, via Slashdot:
Hm. Seems satnav - the article says GPS, with no mention of ГЛОНАСС, but maybe the writer just doesn't realize there's more than one system, and lumps it all under "GPS" - gives wildly erroneous readings in the vicinity of the centuries-old fortress complex that's the center of the Russian government.
Such a mystery!
There's speculation that it's some sort of drone repellent.
Hm, yeah. Maybe it's meant to keep toy aircraft away. Or toy aircraft carrying high-def video cameras. Or toy aircraft carrying grenades or bottles of [list of suggested chemicals omitted].
Or it could be intended to make life more difficult for attackers using homebrew precision-guided munitions: get within [radius, possibly varying] of the target, and you need to go ballistic, or switch to much-trickier inertial navigation (or FPV, which is easily jammed if spotted, and what do the WiFi bands already look like around the Kremlin?).
I assume U.S. cruise missiles have good inertial navigation systems for terminal guidance (and dealing with GPS anomalies, assuming they use GPS at all). ICBMs are, well, ballistic.
So we may speculate that the Russians are worried about non-state actors and rabid-poodle states, and perhaps also are trying to make life more difficult for spies and inquisitive teenagers.