STOCKHOLM, SWEDEN — An intelligence operation to investigate underwater activity near the Swedish capital has confirmed that a foreign submarine violated Swedish territorial waters last month, but it remains unknown which country was responsible, the Scandinavian country said Friday.
The incident occurred in mid-October when the Swedish Armed Forces said it had received "credible information" about foreign underwater activity in the Stockholm archipelago of the Baltic Sea. The report sparked Sweden's biggest military mobilization since the Cold War, involving naval, ground and air units.
Supreme Commander Sverker Göranson of the Swedish Armed Forces said Friday that a recent analysis of all available data confirmed an incursion by a small, green submarine deep into the country's territorial waters. "There is no doubt, we have excluded all other explanations. Swedish territory has been seriously and unacceptably violated by a foreign power," he said.
Göranson said the conclusion was the result of a sophisticated operation in addition to observations reported by civilians. Specific details about the findings were not released, citing concerns that the disclosure of all available data could reveal information about Sweden's capabilities to track territorial violations.
Information about other observations were made public, however. An analysis of a photo taken by a member of the public concluded with "the second-highest level of assessment grading" that it shows the kind of spray that arises when water is pushed out of scuttles at the top of a submarine, which is estimated to have moved at a speed of about 1 knot (1.8 kilometer or 1.1 mile per hour) at the time of the photo.
Another observation was made by a resident who observed an "underwater body with distinctive features." Sensors of the Swedish Armed Forces also found echoes in the area, which was corroborated by "multiple credible sources." A further observation came from a naval corvette which, after picking up information on its sensors, found "recently made traces" on the sea floor.
Swedish Prime Minister Stefan Löfven condemned the incursion and said the government will move to strengthen its capabilities to detect and identify such events in the future. "We do not know who is behind the reported violation. But let me say this, loud and clear, to those who are responsible: this is completely unacceptable," he said.
Löfven said the situation in Ukraine, Iraq, and Syria, among others, reflected a deterioration in the global security situation, but emphasized that there is no indication of any acute danger to Sweden. "A security policy council will be set up at the Government Offices that will meet regularly to coordinate the management of issues relating to Sweden's security. I myself will lead the council," the prime minister said.
Löfven added: "Sweden has a coastline as long as the entire east coast of the United States. No naval force in the world can control such an area in a way that guarantees one hundred percent that no unauthorized party finds its way in underwater. But what we can do is to increase the risk of detection."
The prime minister noted that Sweden has not been directly involved in any wars since 1814 but warned that it will demand respect for its territorial integrity. The Scandinavian country has remained largely neutral over the past 200 years and is not part of any military alliance such as NATO.
"Anyone considering entering Swedish territory unlawfully should also be aware of the enormous risks involved," he said. "We will defend our territorial integrity with all the means at our disposal. And I would like to remind everyone that the Swedish Armed Forces have all the authority needed in a critical situation to prevent a foreign vessel from escaping, including military force as a last resort."
Löfven did not comment on speculation that Russia may have been responsible for the incursion. "As a government and as responsible politicians, we must act above all, and solely, on the basis of facts," he said. Moscow has repeatedly denied any suggestion that it was involved.