So far there have been five reported sightings of a foreign submarine in Swedish waters in the last five days. Sweden has more-or-less said it is likely a Russian intruder. Needless to say the Russian defense ministry has denied that is the case, suggesting it might be a Dutch boat.
The Swedes are right to be concerned. With Mr. Putin's recent activity in the Crimea and Black Sea area, all his neighbours are nervous, and none more so than the Baltic states. Finland has been scrambling jets on a regular basis to respond to Russian incursions into their airspace.
Estonia, Latvia and Lithuania are potential targets for Russian "protection" of Russian minorities, in the same way that similar minorities are currently being "protected" in Ukraine.
Sweden, like many western nations, is still enjoying the so-called peace dividend--the reduction in defense budgets following the supposed end of the Cold War. As a result, Sweden's ability to detect, track, and force to the surface an undersea intruder is severely compromised. The Swedes and their neighbours may have reason to rethink their priorities.
For a look at submarine operations in earlier Cold War years, have a look at "Terror on the Alert", my thriller set in the time of the Cuban Missile Crisis. It's available at bookstores everywhere, or from Amazon or publisher TouchWood Editions.