26 February: According to a statement from the Swedish Security Service (SAPO), an individual has been arrested in central Stockholm on suspicion of “unlawful intelligence activities”. Daniel Stenling, head of the Counter-Intelligence Division of SAPO said that the individual had been recruited by a Russian intelligence officer, probably in 2017. The investigation is ongoing. You can read the statement here:https://www.sakerhetspolisen.se/en/swedish-security-service/about-us/press-room/current-events/news/2019-02-27-individual-arrested-on-suspicion-of-having-carried-out-unlawful-intelligence-activities-against-sweden.html
SAPO employs around 1400 people most of whom are based in Stockholm, but there are also six regional offices. As a near neighbour, Sweden has a long history of countering Russian intelligence attacks. It is particularly wary of Russian submarine activity. As they have strengthened their defences against this threat they have become increasingly concerned about midget submarine activity and underwater drones. These can be launched from Russian mother ships from outside Swedish waters and can be considerably harder to detect.