According to the deputy head of the operation, Rear Adm. Anders Grenstad, such a foreign submarine activity is "unacceptable."
Earlier today, it was announced that the Swedish military ceased operation on searching an unknown underwater object off the coast of Stockholm after a week of search.
The military did not clarify what object was being sought, referring to increased operation secrecy.
According to Swedish media, the military were looking for Russian submarine.
The Russian Ministry of Defence denied the assumptions that the operation carried out in Sweden was allegedly associated with the presence of Russian submarine off the coast of the Scandinavian country.