Who is actually obstructing airliners’ GPS in the Baltic?

.ON APRIL 29TH Finnair, Finland’s nationwide airline company, stated that it would put on hold tours to the asian Estonian city of Tartu for a month. Last week 2 aircrafts were compelled to shift after their general practitioner signals were actually interfered with. General practitioner playing has actually boosted dramatically in the Baltic location over recent 2 years.

Who is behind it and also exactly how hazardous could it be actually?