Marking an escalation in rhetoric over the alleged incursion, Gen Sverker Goeranson said Sweden wanted to send "a very clear signal" that its armed forces were "acting and are ready to act when we think this kind of activity is violating our borders. Our aim now is to force whatever it is up to the surface… with armed force, if necessary," Censor.NET reports citing the National Post.
The supreme commander's words marked a change of tack in what has previously been described as an "intelligence operation" to establish the source of "foreign underwater activity" in the Baltic, close to Stockholm.
His comments raised the spectre of an international stand-off if Sweden employs depth charges to goad the vessel up from below.
The unidentified vessel was spotted surfacing in the Stockholm archipelago twice on Friday and once on Sunday, and Gen Goeranson said yesterday there had been further observations in the past 24 hours. A force of up to 200 men with fast-attack boats, minesweepers and helicopters are combing the area.
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While the armed forces have refused to say they are hunting a submarine or to identify who they believe is controlling the mysterious craft, military analysts believe it is most likely a Russian submarine or mini-submarine.