The shallow waters of the Baltic Sea have become a secondary arena of confrontation in the larger standoff between the East and the West. Fears of hybrid warfare, coupled with key vulnerabilities on both sides, make this narrow stretch of water one of the key areas to watch as hybrid warfare activities expand and NATO bolsters its eastern flank. (Defense News.)
Recent events show just how seriously both sides are taking the challenge.
Soon after the cables were cut, armed vessels from several Baltic Sea states, including Denmark, Sweden and Germany, approached a Chinese ship that they suspected of having been responsible for the rupture, the Yi Peng 3, making its way toward the Atlantic. Visible damage on the ship’s anchor and hull, seen by journalists from a Danish state broadcaster, suggested it may have dragged its anchor across the sea floor in an effort to cause damage.
Satellite-based ship tracking data implies a tense standoff with the ship stopped just a short distance outside of Danish territorial waters and being watched over by armed European vessels. A Russian warship was keeping nearby, spotted on satellite imagery. The ship’s owner, China-based Ningbo Yipeng Shipping, told the Financial Times that “the government has asked the company to cooperate with the investigation.”
It wasn’t the first time that undersea infrastructure in the Baltic Sea mysteriously and violently disconnected. It wasn’t even the first time that a Chinese cargo ship had dragged its anchor across a cable connecting two NATO states and caused considerable damage in doing so. In October 2023, the Newnew Polar Bear damaged a gas pipeline and data cables in the same manner.
So, what is going on in the Baltic Sea, and why is it suddenly so important?
A NATO ‘lake’?
With the recent accession of Finland and Sweden – two previously longtime neutral states – to NATO, many Western observers triumphantly declared the 386,000 square kilometer sea a “NATO lake.” Russia, whose empire once controlled roughly half the coastline here, now holds on to only about 700 kilometers around Saint Petersburg and its Kaliningrad exclave wedged between Lithuania and Poland. Both are incredibly valuable to Moscow: Kaliningrad is heavily militarized and serves as the headquarters of the Baltic fleet, while Saint Petersburg is one of the region’s most important financial centers and plays a major role in Russian foreign trade.
Kaliningrad is also Russia’s only year-round ice-free port in the Baltic. And the territory’s forward position much closer to Western Europe makes it prime real estate for stationing bombers and missiles, according to Moscow’s calculus.
For Russia, as for the other states sharing the Baltic coastline, the sea and its narrow connection to the open Atlantic through the Danish Straits is a crucial link to global trade and commerce. Things get crowded there: Around 2,000 ships are in the Baltic at any given time, and the trade volume amounts to about 15% of the global total, according to the Baltic Marine Environment Protection Commission HELCOM.
The cutting of undersea cables is not a new hybrid warfare tactic. During World War I, both the British and German navies severed the opposing side’s underwater telegraph lines. The idea of hybrid warfare likely has become attractive for Russia due to the military imbalance with the West: Moscow avoids engaging in outright war by employing plausible deniability while still having the potential to undermine Western infrastructure, resolve and cohesion, explained Sebastian Bruns, a senior researcher at the Kiel, Germany-based Institute for Security Policy at Kiel University (ISPK).
“With thousands of kilometers of cables spread across the world’s oceans, it is practically impossible to ‘protect’ them all in an efficient way,” said Basil Germond, a professor of international relations at Lancaster University who researches naval affairs and maritime security. Instead, redundancy and deterrence must be employed. If a network is redundant enough, there will be no significant impact from an attack unless it is large-scale and coordinated, he argued.
The crowdedness and strategic importance of the Baltic to its neighbors means that it has played a central role in these countries’ defense policies. For Russia, access to the Baltic Sea is vital to keep Kaliningrad supplied, as the exclave lacks a direct land connection to Russia and is surrounded by NATO members. To others, like Sweden, it presents the country’s longest frontier and one that is remarkably tough to guard: With archipelagos, bays and sounds, there are plenty of places for unwelcome guests to hide, which led to repeated submarine hunts during the Cold War years.
As a result, Sweden and other Baltic states have developed uniquely adapted navies and military doctrines for the Baltic littoral environment. The Swedish navy operates a fleet of five submarines designed for brown-water operations near land – and is constructing two more – in contrast to the blue-water, deep-sea navies of other NATO states, and a set of seven minesweepers and other boats designed to operate close to shore.
The Baltic Sea is a unique environment, boasting an average depth of just around 55 meters. It is also considered brackish water (an in-between level between salt- and freshwater) due to the many rivers that empty into it. Layers of varying salinity provide ideal conditions for submarines to hide, especially the smaller ones capable of operating in the Baltic in the first place.
States around the Baltic Sea have been some of Ukraine’s most ardent supporters, given their own proximity to Russia. Particularly the Baltic nations have sent outsized contributions to Kyiv’s defensive war effort: Estonia and Lithuania gave 1.8% of their GDP to Ukraine and Latvia 1.5%, according to a report by the Wilson Center, a Washington-based think tank.
In September, NATO announced it would open a naval command center for the Baltic Sea in the German coastal city of Rostock to “coordinate naval activities in the region” and provide NATO with a “maritime situation picture in the Baltic Sea region around the clock,” according to the German military. Staff from 11 other alliance countries will be present at the HQ.
