The Swedish government back then attributed only two of these submarines to the soviets, one of them being the stranded Whiskey sub. The second case was also later disputed.
I think you understand that the author isnt talking about the Whiskey sub being invented or staged.
To "most", the sentences after your quote is the interesting one.
> Classified documents point to covert US and UK activity. Former US secretary of defense Caspar Weinberger stated that Western submarines operated ‘regularly’ and ‘frequently’ in Swedish waters in order to ‘test’ the Swedish coastal defences, and former British navy minister Sir Keith Speed confirms the existence of such operations. Royal Navy submarine captains admit having carried out top-secret operations in Swedish waters, and that a member of Cabinet signed approval for every single operation
Here is a different source if you prefer that.
https://www.apnews.com/f0a9cfd83c430978e6545b902f1160d2
