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In October 1981, the Soviet submarine S-363 accidentally hit an underwater rock about 10 kilometres (6.2 mi) from the main Swedish naval base at Karlskrona, surfacing within Swedish waters. The boat's presence coincided with a Swedish naval exercise, testing new equipment, in the area. Swedish naval forces reacted to the breach of sovereignty by sending an unarmed naval officer aboard the boat to meet the captain and demand an explanation. The captain initially claimed that simultaneous failures of navigational equipment had caused the boat to get lost (despite the fact that the boat had already somehow navigated through a treacherous series of rocks, straits, and islands to get so close to the naval base). The Soviet navy would later issue a conflicting statement claiming that the boat had been forced into Swedish waters due to severe distress, although the boat had never sent a distress signal, and instead attempted to escape.
The Swedes were determined to continue investigating the circumstances of the situation. The Soviet captain, after a guarantee of his immunity, was taken off the boat and interrogated in the presence of Soviet representatives. Additionally, Swedish naval officers examined the logbooks and instruments of the submarine. The Swedish National Defence Research Institute also secretly measured for radioactive materials from outside the hull, using gamma ray spectroscopy from a specially configured Coast Guard boat. They detected something that was almost certainly uranium-238 inside the submarine, localized to the port torpedo tube. Uranium-238 was routinely used as cladding in nuclear weapons and the Swedes suspected that the submarine was in fact nuclear armed. The yield of the probable weapon was estimated to be the same as the bomb dropped over Nagasaki in 1945. Although the presence of nuclear weapons on board S-363 was never officially confirmed by the Soviet authorities, the vessel's political officer, Vasily Besedin, later confirmed that there were nuclear warheads on some of the torpedoes, and that the crew was ordered to destroy the boat, including these warheads, if Swedish forces tried to take control of the vessel.
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#SVEAWAVE #Försvarsmakten #HållGränsen