Following the stranding of a Soviet Whiskey-class submarine in 1981 on the Swedish archipelago, a series of massive submarine intrusions took place within Swedish waters.
However, the evidence for these appears to have been manipulated or simply invented. Classified documents and interviews point to covert Western, rather than Soviet activity. This is backed up by former US Secretary of Defense Caspar Weinberger, who stated that Western "testing" operations were carried out regularly in Swedish waters. Royal Navy submarine captains have also admitted to top-secret operations.
Ola Tunander's revelations make it clear that the United States and Britain ran a "secret war" in Swedish waters. The number of Swedes perceiving the Soviet Union as a direct threat increased from 5-10 per cent in 1980 to 45 per cent in 1983. This Anglo-American "secret war" was aimed at exerting political influence over Sweden. It was a risky enterprise, but perhaps the most successful covert operation of the entire Cold War.