Joggers, taxi drivers, Pokemon Go players and senior Russian officials are seeking answers as to why mobile phone apps that use GPS are malfunctioning in central Moscow.
A programmer for Russian internet firm Yandex, Grigory Bakunov, said his research showed a system for blocking GPS was operating from the Kremlin, the heavily guarded official residence of president Vladimir Putin.
People have complained on social media that when they are near the Kremlin their GPS-powered apps show them to be in Vnukovo Airport, 18 miles away.
The problem has frustrated those requesting taxis through services such as Uber or looking to catch Pokemons in the popular game played on mobile devices.
Large numbers of people running the Moscow marathon last month complained that their jogging apps lost track of how far they had run when they passed the Kremlin.
"I got 40 kilometres added on to my distance. It happened by the Kremlin," runner Andrey Yegorov wrote on Facebook as part of a discussion by runners.
The link to Vnukovo Airport, according to Mr Bakunov, suggests the purpose of the disruption may be to prevent drones flying over the Kremlin.
GPS often automatically stops drones from flying near airports because of the danger they present to aircraft. Any device mimicking this would be able to halt overflights.
The first anomaly was recorded in June, according to Russian media reports, which have also suggested that the GPS interference comes and goes in a pattern.
Mr Putin's spokesman Dmitry Peskov said he did not know why the malfunction was occurring but admitted experiencing the problem himself when driving recently.
He redirected questions to Russia's Federal Guards Service, which is responsible for protecting the Kremlin and senior Russian officials.
A spokesman for the Federal Guards Service declined to comment.