STOCKHOLM, Sweden -- Sweden's military on Friday sent naval vessels, aircraft and home guard forces to investigate reports of "foreign underwater activity" in the Stockholm archipelago.
The Armed Forces said they launched an intelligence operation in the archipelago after receiving information "from a credible source."
Armed Forces spokesman Jesper Tengroth wouldn't say whether a submarine had been sighted or give any other details.
Chief of operations Jonas Wikstrom told reporters "a few hundred" people were taking part in the search.
The operation was reminiscent of the Cold War, when Sweden's armed forces routinely hunted for Soviet submarines in its waters.
In 1981, a Soviet sub carrying nuclear weapons got stranded off Sweden's southeastern coast, causing an 11-day diplomatic standoff before Swedish authorities allowed the submarine to return home.
Swedish officials wouldn't speculate on what foreign power could be behind the suspected intrusion Friday.
Sweden's Foreign Ministry last month summoned the Russian ambassador to protest a Swedish air space violation by two Russian military aircraft.
