This is not official and still classified.
My sources are interviews made by swedish newspapers, books and documentaries.
During the 50s the signals intelligence equipment was placed in DC-3s. And pretty often the DC-3s crossed SU territory, SU usally responded by sending 1-5 Mig-15s and Mig-17s to make the plane leave their territory. But 13.19-13.27, 13th June 1952 a DC-3 filled with american equipment got shot down by a Mig-15. All eight in the DC-3 died and the plane smashed in the baltic sea near the Sweden/SU border. SU denied this have happened. The 16th June 1952 a swedish Catalina aircraft was searching for the DC-3 when it was attacked three times by several Mig-15 on Swedish territory. The pilot manage to land in the water but the Catalina sunk very fast, all crew members survived. SU stated that it had entered SU territory.
SU flight chart for target 303(blue) and Mig-15-fighter(red)
12.15-13.44, 13-06-1952.
http://www.mil.se/images/local/flygkarta.gif
Through out the 60s, 70s and 80s it got really tensed between Sweden and SU. In the 60s Sweden signed a top secret treaty with USA that in case of war Sweden will be granted access to USA nuclear-weapons and it was dugged up that the swedish supreme commander shared information about the Swedish Air Force tactics, numbers and aircrafts peformance with SU.
In the mid 60s Sweden together with NATO had found out where the SU radar stations in the baltics were based. So Sweden got ordered by USA/NATO to "test" the SU Air Force time to respond against a attack from the air.
The swedish plan was to order take-offs to 10-100 Draken fighters from several fighter wings across Sweden. Then these pilots would select a spot to form a tight formation and start cruise at 950 km/h at low altitude across the Baltic sea with the radar switched off. Just before they cross the Sweden/SU border they scatter the formation, climb to high altitude, turn on their radars and light their afterburners to reach mach 2,05. When this was done they continue until they could register SU-figthers on their radars, then do a fast turn and leave SU territory in a light dive to increase the speed. This happened at least once every third month. Sweden also did this with Viggen fighter/bombers in the 80s. SU also did this a few times mostly against Gotland.
Between 1980-1994 Sweden registered 45000 underwater objects near the coast and in the baltic sea. And in October 1981 U-137 probably armed with nuclear warheads, hit rock bottomonfloorl: ) well, not rock but sand. This happened inside a military protective area near. This almost got Sweden and SU to a conflict because in the begining Sweden refused to let SU ships towe the sub. This continued and it became a small arms race, Swedish Armed Forces brought rangers, subs, corvettes, helicopters to the area and SU brought several frigates, subs to stand by outside the swedish border. SU tried many times to get other subs to the area but was stopped by swedish helicopters and torpedo-boats.
This is a very intersting topic. All these things is probably just the tip of a huge iceberg.
My sources are interviews made by swedish newspapers, books and documentaries.
During the 50s the signals intelligence equipment was placed in DC-3s. And pretty often the DC-3s crossed SU territory, SU usally responded by sending 1-5 Mig-15s and Mig-17s to make the plane leave their territory. But 13.19-13.27, 13th June 1952 a DC-3 filled with american equipment got shot down by a Mig-15. All eight in the DC-3 died and the plane smashed in the baltic sea near the Sweden/SU border. SU denied this have happened. The 16th June 1952 a swedish Catalina aircraft was searching for the DC-3 when it was attacked three times by several Mig-15 on Swedish territory. The pilot manage to land in the water but the Catalina sunk very fast, all crew members survived. SU stated that it had entered SU territory.
SU flight chart for target 303(blue) and Mig-15-fighter(red)
12.15-13.44, 13-06-1952.
http://www.mil.se/images/local/flygkarta.gif
Through out the 60s, 70s and 80s it got really tensed between Sweden and SU. In the 60s Sweden signed a top secret treaty with USA that in case of war Sweden will be granted access to USA nuclear-weapons and it was dugged up that the swedish supreme commander shared information about the Swedish Air Force tactics, numbers and aircrafts peformance with SU.
In the mid 60s Sweden together with NATO had found out where the SU radar stations in the baltics were based. So Sweden got ordered by USA/NATO to "test" the SU Air Force time to respond against a attack from the air.
The swedish plan was to order take-offs to 10-100 Draken fighters from several fighter wings across Sweden. Then these pilots would select a spot to form a tight formation and start cruise at 950 km/h at low altitude across the Baltic sea with the radar switched off. Just before they cross the Sweden/SU border they scatter the formation, climb to high altitude, turn on their radars and light their afterburners to reach mach 2,05. When this was done they continue until they could register SU-figthers on their radars, then do a fast turn and leave SU territory in a light dive to increase the speed. This happened at least once every third month. Sweden also did this with Viggen fighter/bombers in the 80s. SU also did this a few times mostly against Gotland.
Between 1980-1994 Sweden registered 45000 underwater objects near the coast and in the baltic sea. And in October 1981 U-137 probably armed with nuclear warheads, hit rock bottomonfloorl: ) well, not rock but sand. This happened inside a military protective area near. This almost got Sweden and SU to a conflict because in the begining Sweden refused to let SU ships towe the sub. This continued and it became a small arms race, Swedish Armed Forces brought rangers, subs, corvettes, helicopters to the area and SU brought several frigates, subs to stand by outside the swedish border. SU tried many times to get other subs to the area but was stopped by swedish helicopters and torpedo-boats.
This is a very intersting topic. All these things is probably just the tip of a huge iceberg.