The military underwater hunt has ended with no concrete evidence of what caused the alert.
But during the search newspaper Svenska Dagbladet had reported sources which claimed the hunt took place in the context of an encrypted distress signal between a point in the Stockholm archipelago and the Russian enclave of Kaliningrad, between Poland and Lithuania.
Dagens Nyheter requested the documents concerning the signal's interception.
The military usually replies that the documents are classified. This time they were not even able to do that.
"Nothing like that exists, the report is false," says one of Dagens Nyheter's own anonymous sources, within naval intelligence.