In the media the current intelligence operation south of Stockholm has been described as the Swedish Navy searching for (or even hunting) “a Russian submarine”. I would like to point out that the picture might be quite a bit more complex. As said earlier, out of respect for the fact that it is an ongoing operation and the possible need for OPSEC, I will not include any attempts at an OOB.
The Swedish Defence Forces yesterday (Friday the 17th of October) stated that during the day they had received information from a reliable source about “foreign underwater activity”. As a response to this, the Swedish Defence Forces have decided to conduct an intelligence gathering operation in the area, with sea, air and land units.
The “foreign underwater activity” was immediately translated into “Russian submarine” by the media. There are Russian submarines in the Baltic Sea, namely the two ‘Kilo’-class submarines B-227 Vyborg and B-806 Dmitrov of Projects 877 and 877EKM respectively.
However, there are a number of other possible explanations.
The possibility of Russian divers and/or light underwater equipment has to be accounted for. This could include midget submarines or diver propulsion vehicles, with either a supporting land-based unit, or support from ships/submarines in international waters. Possible missions include intelligence gathering, e.g. with regards to the ability of the Swedish units to detect and respond to incursions of this kind. This kind of mission would most probably go to Russian naval Spetsnaz units, which made headline during the 2008 war in Georgia when they apparently entered into the port of Poti and destroyed the majority of the surface units of the small Georgian Navy.
Another possibility is that some other country sent a submarine into the area.
Poland operates a single Project 877E ’Kilo’-class as well as four German-designed Ex-Norwegian Type 207 ’Kobben’-class submarines. All are of the diesel-electric type, meaning they are extremely quiet when submerged, but have to go up to the surface and recharge their batteries every now and then. Although the submarines are somewhat dated, they still constitute a very proficient striking force.
Germany has continued its long and proud tradition as builder of submarines. Currently its submarine force consists of four Type 212 A submarines based in Eckernförde, close to Kiel. These are some of the most modern submarines in the world, being so called AIP-submarines (air independent), meaning that thanks to their hydrogen fuel-cells they don’t have to surface regularly.
Neither the three Baltic countries nor Denmark has any submarines left. Sweden has three Gotland-class and two Södermanland-class AIP-submarines, but these are naturally not part of the equation. However, the Netherlands currently has a single Walrus-class submarine in the Baltic Sea, which has taken part in exercise Northern Archer together with the Swedish units now scanning the waters south of Stockholm. As far as I know, no details about its route home have been published.
It is possible that some of these countries have decided to test the Swedish response to underwater incursions. It could have been a unilateral decision by the country in question, or as a proposal/request/idea from some kind of higher-level NATO forum. The purpose in that case would most probably be intelligence gathering, to get a validated picture of the Swedish response and capabilities in case of a Russian incursion, where the secondary goals could include highlighting these deficits in capability to the Swedish politicians and general public. The Navy is already well aware of its (lack of) capabilities.
This would naturally be a very high-risk operation politically, as getting publicly caught with your submarine in the territorial waters of a friendly country is not desirable, to put it mildly. To lessen the risk, a similar operation could naturally be launched with divers as discussed above in the case of Russian units.
I will not rank any of these scenarios as to what is most likely, but bear in mind, there are a lot of things happening under the surface of the Baltic Sea about which we know very little.
Edit 18/10/2014 18:15 (GMT +2): On the press conference that just finished, it became clear that the Swedish navy increases number of units involved in intelligence operation outside Stockholm, stresses focus is on intelligence NOT on subhunt. They still believe the original intel about foreign underwater activity was “very reliable”, and declines to comment on “What further circumstantial evidence we have received”. No further specifics were revealed.