Writing in his blog, the foreign minister said that the latest findings should not be taken in isolation. Instead the Hårsfjärden charter boat Amalia should be "added to the very long list of other indications and information from that area at that time."
Bildt was himself a member of the submarine commission that urged Olof Palme's Social Democratic government to lodge a formal and strongly worded protest to the Soviet Union.
"Since then - if I remember correctly - three different commissions have looked at all the available information about these incursions from every possible angle and have largely reached the same conclusions," wrote Bildt.
The 3 minutes and 47 seconds of tape recorded by the marines on October 12th 1982 was the government's strongest piece of evidence at the time.
By employing new methods to analyze the old tape, the Swedish Defence Research Agency (FOI) has now been able to determine that the sound in all likelihood originated from the passing charter boat Amalia.
But Bildt further noted that "FOI has also analyzed a so-called ping sound from a hydrophone that was apparently on the same tape."
The agency was not able to rule out the possibility that the sound might have come from an underwater microphone deployed by a foreign vessel, said Bildt.