Lessons from Sweden’s Sub Hunt

October 28, 2014 9:56 AM - Updated: October 28, 2014 1:27 PM


The Swedish navy was pushed into its largest anti-submarine effort since the close of the Cold war last week.

For six days, it hunted for an unknown foreign submersible, likely from Russia, spotted several times off the coast close to the capital of Stockholm.

The Swedes called off the search on Friday without finding the mystery craft, but reportedly collected a trove of intelligence information for further analysis.

The search for a mystery submersible says much about the state of the Swedish navy in particular, and European fleets in general. It should also prompt a new effort to address the need for high-end warfighting capabilities across European navies.

The Hunt

Swedish sailors hunt for mystery submarine last week. Photo via ABC News
Swedish sailors hunt for mystery submarine last week. Photo via ABC News

Called an intelligence gathering operation—the effort off the coast of Stockholm lasted for nearly a week and included surface combatants, helicopters, ground troops (to sweep the islands in the Stockholm archipelago)—and more than likely one or more of Sweden’s air independent propulsion (AIP) attack submarines.

The mystery deepened when Sweden’s largest daily, Svenska Dagbladet, reported that the Swedish signals intelligence agency had intercepted emergency communications between a transmitter off the coast of Sweden and Kaliningrad—the home of Russia’s Baltic fleet—which suggested that the intruding submarine might be in distress.

A Russian merchant vessel, the NS Concord, circled just outside Swedish territorial waters throughout the operation, leading many to think that it was serving as a mother ship, and that the Swedish navy was tracking the scent of a Russian mini-submarine far inside Swedish waters.

There are several theories to what this mini-submarine could be doing so far into Swedish territorial waters, including that it was an exercise under real operational conditions for Russia’s naval special forces, or that the mini-submarine was deploying or replacing sensors in order for the Russian Baltic fleet to be able to monitor the movements of the Swedish navy in and out of their bases.

The most likely explanation seems to be that the mini-submarine was there to observe the multinational naval exercise Northern Archer, in which Swedish, Dutch, Danish and Polish naval units met up for training, including anti-submarine warfare (ASW).

The operation was called off after six days of intense efforts, with no visible results—although the Swedish armed forces say they have collected a trove of intelligence that now needs to be further analyzed. Regardless of the final outcome, the ASW operation says much about the Swedish and European navies, and the emerging maritime environment in and around Europe.

ASW in the Baltic Sea Then and Now


This was far from Sweden’s first ASW operation. During the 1980s the Royal Swedish Navy conducted a number of prolonged and intense operations against suspected Soviet submarines in and around coastal areas in the vicinity of naval bases and defense installations.

Some operations even included the use of live weapons against subsurface contacts. The most well known incident during this period is the so-called Whiskey on the Rocks grounding, when a Soviet Whiskey-class submarine ran aground only a few nautical miles from the inlet to the Swedish naval base in Karlskrona.

The Soviet sub was eventually towed into international waters by the Swedes, after a tense stand-off between the Swedish military and the Soviet Baltic fleet. The incident is now remembered in Sweden as perhaps the most important moment in the country’s Cold War history.

ASW helped define the Swedish navy during this period, and over roughly two decades the Swedes built up a muscular ASW force that could detect, target and attack submarines from above, on and below the surface. That generation of Swedish naval officers was essentially forged during the grueling ASW patrols off Sweden’s east coast.

Subsurface sensors and mine lines were strung across likely passages in and out of Stockholm, vital ports, and naval bases. That the Swedes attained so few tangible results says less about their ASW proficiency than about the forbidding conditions in the Baltic Sea, where the shallow depths (with an average of less than 200 feet), brackish water, and large archipelagos combined to make sub-hunting a tricky and frustrating proposition.

The Swedish submarine force used the same conditions to great effect. The skills, tactics, and technology honed in that environment made the submarine HMS Gotland a tough adversary for the U.S. Navy between 2005 and 2007, when the Swedish submarine was homeported in San Diego with its crew, to serve as an opponent during U.S. Navy ASW exercises.

However, the operation last week served as a stark reminder that the Swedish navy has changed considerably over the past two decades.

The Swedish ASW force that left port to hunt for the suspected submarine was in some ways more capable (including the stealth corvette HMS Visby), but considerably smaller than the force Sweden put to sea in the 1980s.

Since the Cold War, Sweden’s surface fleet has shrunk from 34 combatants to only nine and from 12 attack submarines to only five. To boot, Sweden scrapped its ASW helicopters a few years ago, and the replacement platform is not due to enter service until 2018 at the earliest.

While Swedish warships and submarines are all high quality, the navy has now reached a point where quite arguably quantity has become a quality in its own right, and the small numbers hamper the navy’s ability sustain operations for any longer period of time, or the ability to surge presence in a given area.

Furthermore, the Swedish navy has spent hardly any time on developing and exercising ASW tactics over the past decade. Instead, it has focused on expeditionary operations in concert with NATO, the European Union and the United Nations. Swedish units have participated in the naval embargo off Lebanon in 2006, and have also sustained a long commitment to the counterpiracy operation off the Horn of Africa. Much of the training and exercising in the past decade has been focused on supporting these types of maritime security operations.

European Navies and High-End Naval Warfighting

This development makes the Royal Swedish Navy in no way unique among European navies. There has been a general trend of a declining number of hulls in European navies, along with a focus on maritime security operations and supporting operations ashore. Along with the aforementioned operations, European navies have also contributed to operations Active Endeavor and Unified Protector in the Mediterranean and the removal of Syrian chemical weapons via the sea.

While all were important efforts they were focused on either the lower end of the maritime threat spectrum, or in support of operations ashore. And some have even gone further than the Swedes in optimizing their militaries for expeditionary operations and “small wars.” Denmark, for example, scrapped its entire submarine force in the early 2000s, in order to husband the resources needed to craft a more expeditionary navy, which has admittedly acquitted itself quite well in, for example, counterpiracy efforts off the Horn of Africa.

Broadly speaking, European navies believed there was little need for ASW and other types of high-intensity operations in age where the United States was unchallenged, Russia was weak, and the major threat against Western security resided in caves in the Hindu Kush. This analysis of the threat environment is not necessarily incorrect, but perhaps only partially true.

European navies and coast guards do indeed deal with very immediate maritime security concerns in the Mediterranean and the Arctic on a daily basis, ranging from large flows of seaborne illegal immigrants to the possibility of oil spills in the fragile Arctic.

A More Competitive Maritime Environment

Swedish sub Gotland at Naval Station San Diego, Calif. with USS Ronald Reagan (CVN-76) in the background. US Navy Photo
Swedish sub Gotland at Naval Station San Diego, Calif. with USS Ronald Reagan (CVN-76) in the background. US Navy Photo

But the recent events in Sweden’s waters strongly suggests that with an ever more assertive Russia, high-end capabilities will be as relevant in the future as they were during the Cold War, and must be developed and maintained alongside the maritime security missions taken on since the 1990s.

Even without worries about Russia, European naval leaders are well aware of China’s emerging sea power, and that the global maritime environment is set to become more congested and competitive than perhaps ever before.
Beyond the Baltic Sea, Russia is also increasingly active in both the Black Sea and the High North.

To respond, NATO (and the United States) should consider doing an ASW exercise together with its Swedish partner in the near future to show an alliance naval presence in the Baltic Sea, and that the transatlantic community is responding to the changing maritime security environment. Thankfully, NATO already seems to be making some efforts in this regard, as the recent naval exercise Noble Justification did indeed include elements of high-intensity combat training.

The hunt for the mystery submarine should also serve as a wake-up call across the European and U.S. naval communities to not assume a benign maritime environment in and around Europe in the coming decades.

Magnus Nordenman

Magnus Nordenman

Magnus Nordenman is the Deputy Director of the Brent Scowcroft Center on International Security at the Atlantic Council in Washington, DC. He writes and speaks on transatlantic security, Nordic-Baltic defense, and US military affairs, most recently on NATO's maritime future. He is a graduate of the Virginia Military Institute and the University of Kentucky.

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