Swedish submarine incidents The submarine hunts or submarine incidents were a series of several incidents involving foreign submarine s that occurred in Swedish territorial waters during the Cold War , more specifically during the 1980s . In this time , there was intensive debate and speculation in Swedish media about the possibility of Soviet submarine infiltration of Swedish territorial waters . While there had been earlier incidents involving foreign submarines ( as seen below ) , the incidents normally referred to in this context are those that followed the sensational stranding of the Soviet submarine " U 137 " deep inside Swedish waters on October 27 , 1981 . The Swedish navy responded aggressively to these perceived threats , increasing patrols in Swedish waters , mining and electronically monitoring passages , and repeatedly chasing and attacking suspected submarines with depth charge bombs , but no hits or casualties were ever recorded . Reports of new submarine sightings and television imagery of Swedish Navy helicopters firing depth charges into coastal waters against suspected intruders became commonplace in the mid - to - late 1980s . They remain , for many Swedes , one of the iconic images of the Cold War and of the Swedish relation to the Soviet Union — for some underlining what was considered a major threat to Swedish sovereignty , while for others illustrating the tense and , in the view of some , paranoid atmosphere of the time . However , the reports of these incidents are not uncontested , and an intensive debate emerged early on . This debate unfolded somewhat , but far from exclusively , along leftwing / rightwing lines , and became tied up with the larger issues of relations to Moscow and Swedish armed neutrality . The Soviet Union consistently denied that it was responsible for violating Swedish waters , and claimed that the U 137 had only crossed the border because of navigational faults . Russia today maintains this stand . While the submarine sightings subsided with the fall of the Soviet Union , the debate about these events has reemerged in the 1990s and 2000s ( decade ) . They have been the subject of a number of government investigations in Sweden , and continue to attract media attention . Controversy . As noted above , these events have been hotly disputed in Swedish media and by politicians and journalists active during the time . Although there were some clearly recognized cases of foreign military activity in Swedish waters ( e . g . band tracks on the sea floor , or most obviously the U 137 ) , many of the supposed submarine incidents were based on intelligence reports , radar , underwater sensors , or witness statements , giving a less than full picture of the source of the disturbance . As a result , there is no clear consensus on the extent of possible infiltration , or on whether trespassing submarines were necessarily of Soviet origin . Some suggest that NATO submarines may have been responsible for the most well - known incidents , which has led to a further line of debate , on whether such submarines were secretly allowed to exit Swedish waters unpursued — that would have been in contravention of the publicly declared Swedish neutrality . There is also a dispute concerning sound recordings purported to be of submarine engines , which some now allege stem from natural sounds , fish , mink , civilian vessels , etc . The discussion also focuses on whether " U 137 " was sent to spy on Swedish defenses ( supported by the large number of similar suspected espionage infiltrations , and by the depth to which it had penetrated ) , or , as its captain claimed , was lost because of a navigational error ( supported by the fact that it ran aground ) . Furthermore , there is a debate on whether this vessel was armed with nuclear weapons . Swedish military teams are said to have registered high levels of radiation on geiger counter s when examining the stranded submarine . Twenty years after the events , they still generate controversy in modern - day Swedish politics , with prominent politicians and former military officials active on both sides of the dispute . Ola Tunander attributes the majority of these incursions to be of NATO origin . Cultural influence . The incursions during 1982 and 1983 form a basis for the plot of " The Troubled Man " ( " Den orolige mannen " ) , the final Kurt Wallander novel written by Swedish author Henning Mankell and published in 2009 . Mankell considered the incursions to be one of the worst scandals in Swedish political history . Mankell ’ s play " Politik " ' , which debuted in autumn 2010 , also dealt with the submarine incidents .