One of Russia’s most important security policy aims is probably to weaken NATO. An isolated attack on Sweden, nonaligned and militarily weak, could be a quite risk free option to undermine NATO´s credibility when it comes to defending the Baltic States, thereby also affecting the credibility of the alliance as a whole.
Access to Swedish air space, sea and land territory is of vital importance to NATO in conducting military operations in case of a Russian attack on the Baltic States. If Russia was able to deny NATO this possibility it is doubtful if NATO would be able to act fast and strong enough to “save” the Baltic States.
This opens up for a quite an interesting option for Russia. By “borrowing” just some limited parts of Sweden and deploying long range air defence systems there NATO would be put in a position where it would be obvious that the alliance would have great problems delivering substantial help to the Baltic States, at least not in time to prevent an occupation.
The most interesting areas in Sweden for such a Russian operation are Gotland, a large island in the middle of the Baltic, and parts of southern Sweden. On Gotland there is no permanent Swedish military presence except for a home guard unit, making it an easy target. There would be no need for Russia to make extensive and revealing preparations to launch an operation aiming at occupying the island. A surprise attack is a very real option. Russian long range systems deployed there would make air and sea operations on and over the Baltic Sea very hazardous for an opponent. Russia being able to deploy the same systems in southern Sweden would have the same consequences when it comes to limiting NATO´s freedom of action.
Without attacking a member of NATO Russia would have created a situation where, if it put pressure on the Baltic States, the rest of the alliance would have to consider if it is worthwhile starting a major European war to “save” something that is impossible or very hard to “save” anyway – the Baltic States. My guess is that there would be quite heated discussions in Brussels on how to handle such a contingency.
Russia is probably more interested in breaking up NATO and weakening EU than acquiring some extra square kilometers of territory in Latvia or Estonia. Russia could therefore very well abstain from attacking any of the Baltic States once it had created an environment where it had made NATO´s security guarantees hollow, thereby avoiding the risk of NATO following the principle that a member of the alliance will be defended, regardless of cost and the chances of success (England and France regarding Poland 1939).
Russia would instead have created a situation that would open up for different “diplomatic solutions” to “mutual benefit” of the parties involved. Probably not ending up in solutions beneficial neither for the Baltic States nor European security as a whole. And of course also having created a very favorable operational environment if it would chose to pursue a military option.
Sweden’s very limited military capabilities, today and for the foreseeable future, and also not being a member of NATO makes this Russian option far too attractive to be ignored by Sweden, and others, when thinking about security and stability in the Baltic Sea region, and Europe.