Two fiber-optic undersea cables in the Baltic Sea were severed on Sunday and Monday, raising suspicions about a Chinese cargo ship, which the Danish Navy is currently transiting through the Kattegat Strait between Denmark and Sweden.

The Chinese ship, which left the Russian port of Ust-Luga on Friday last week and appeared to pass over the area where the incidents took place, has been named by Swedish police as a “point of interest”. The incident is being investigated.

Swedish Prime Minister Alf Kristerson said on Wednesday that the incident should be investigated, adding: “We have seen sabotage in the past, so we take it very seriously.”

It is the latest in a series of incidents involving pipelines or cables in the Baltic Sea over the past few years. So what’s going on in the Baltic Sea, and what role does underwater sabotage play in the international conflict?

What else has damaged pipelines and cables in the Baltic Sea?

The deep, dark, salty expanse of the Baltic Sea floor has been a hotbed of geopolitical intrigue for two years. Nord Stream gas pipelines, which are owned by a consortium of energy companies including Russian gas company Gazprom and run from Russia to Germany; Shaken by explosions. In September 2022.

More than two years on, no one has claimed responsibility for the blasts, despite plenty of finger-pointing.

The blasts ripped through the Nord Stream 1 pipeline, which began operating in 2011 and was shut down by Russia just weeks before the explosions.

They also damaged the Nord Stream 2 pipeline, which never entered service because Germany withdrew its certification after Russia’s full-scale invasion of Ukraine in February 2022.

Each pipeline consists of two pipes. The explosions disabled three of the four.

Some Western officials blamed Moscow for destroying the pipes.

In April 2023, a joint investigation by the public broadcasters of Sweden, Denmark, Norway and Finland claimed that Russia had deployed a fleet of suspected spy ships in the Baltic Sea for sabotage operations.

Moscow, in turn, blames the United States and its allies, while German and American media have reported that pro-Ukraine actors have played a role.

Since then, tensions have only increased.

Just over a year after the Nord Stream pipeline explosions In October 2023, the Baltic Connector gas pipeline connecting Finland and Estonia – jointly owned by Estonian electricity and gas system operator Elering and Finnish gas transmission system operator Gasgrid – was damaged in an undersea incident. . There are also reports of ruptured data cables nearby.

Investigators from Finland and Estonia have alleged that a Chinese container ship was dragging its anchor offshore. damaged, Which took six months to repair. He did not say whether he believed the damage was intentional.

Why would the Baltic Sea be a hotspot for underwater sabotage?

In short, geography.

The sea has a shallow and narrow basin, has three outposts, and is surrounded by eight NATO countries.

It also borders Russia, with the country’s second largest city, St. Petersburg, located in the eastern corner of the Gulf of Finland and its Baltic Fleet in the Kaliningrad enclave.

Norwegian Defense University College professor Tormod Heyer told Al Jazeera that post-Cold War tensions in the region began in 2004 after three Baltic states – Estonia, Latvia and Lithuania – joined NATO.

He said there was little consideration in the West of how, without a buffer zone, the alliance could “credibly defend the three small Baltic states in NATO”.

Hare said that as Russia “increasingly asserts and challenges the liberal Western world order”, the Baltic Sea region has become the alliance’s “Achilles heel”.

Russia’s full-scale invasion of Ukraine in 2022 and the accession of Sweden and Finland to NATO in 2024 have heightened tensions.

Finland shares a 1,340 km (832 mi) border with Russia and, with its accession, doubled NATO’s border with Russia and squeezed its coastal access to St. Petersburg.

Are these underwater incidents surely sabotage?

It’s impossible to know for sure, but experts say it’s likely.

There is a method of underwater sabotage known as “hybrid warfare” – a military strategy that uses both conventional and unconventional methods to destabilize regions or countries as an all-out form of warfare. is given

Hybrid warfare is nothing new in the region – from GPS jamming over the Baltic states to Russian spy planes flying over the Baltic Sea into Swedish airspace.

Hare says the advantage of hybrid warfare is that it is difficult to attribute directly to a single actor.

This means that the dirty waters of the Baltic Sea provide the perfect “grey zone” in which the indirect, ambiguous nature of a pipeline or cable sabotage incident would still be considered below the “threshold” for outright war. .

Charlie Salonius Pasternak, a senior research fellow at the Finnish Institute of International Affairs, told Al Jazeera that the facts surrounding this week’s incident were still “fuzzy” and that it was “too early to rule or rule out sabotage”.

A range of accidents could lead to underwater incidents, he said, adding: “You have oil-laden ships that have no idea how shallow and complicated it is to operate in the Baltic Sea. “

More than 2,000 ships pass through the Baltic Sea every day, and the number of large ships, including tankers, has increased over the past decades as international trade has grown in the region.

“Darkship” activity has also increased since Western countries imposed sanctions on Russia following its invasion of Ukraine in 2022.

A “dark ship” is a ship that turns off the signal system that transmits its position coordinates, often to prevent interceptions.

To determine the likelihood of sabotage, Hare said, it’s important to consider whether an actor has a “reasonable intent” to aggravate the cable and whether a pattern emerges from those incidents.

Many Western leaders believe a pattern is forming, including Lithuanian Foreign Minister Gabrielius Landsbergs, who on Wednesday sneered at X: “If I had a nickel every time a Chinese ship dropped its anchor The bottom of the Baltic Sea was dragging around the main cables, I would have two nickels, which is not much, but it is strange that it happened twice.”

Salonius-Pasternak said it will take time and expertise to determine whether an incident like Monday’s cable break was an accident.

Professor Ashok Swain, head of peace and conflict research at Sweden’s Uppsala University, told Al Jazeera that this too should be done by a neutral body.

He said individual states have taken responsibility for investigating the incidents so far, raising questions of bias and allowing different parties to blame each other.

Sweden, Denmark and Germany launched three separate investigations into the Nord Stream pipeline explosions in 2022.

Germany’s case continues, but the two Nordic countries have closed their cases with no one being held responsible.

So, if this is underwater sabotage, who can carry it out?

The nature of this form of hybrid warfare means that each country has its own version of the story, Swain said.

After the Nord Stream explosion, some US and European officials initially insisted that Moscow had blown up the pipelines.

However, Russian President Vladimir Putin accused the US and its allies of flying them. The Russian Ministry of Defense at one stage specifically blamed British naval personnel.

In the latest incident, Swedish police said the Chinese vessel Yi Peng 3 was “of interest” and launched an investigation.

Regarding the Chinese ship Yi Peng 3:
Danish Defense can confirm that we are in the vicinity of the Chinese vessel Yi Peng 3. Danish Defense has no further comment at this time. https://t.co/11s3yeR4PB

— Defense (@forsvaretdk) November 20, 2024

One communication cable that was cut ran from the Swedish island of Gotland to Lithuania, while another was between Finland and Germany.

According to maritime data, the Chinese vessel was passing over two cables when they were severed. Possible triggers are unclear.

How is underwater sabotage done?

It depends on the event.

Seismologists in Denmark and Sweden suggest that the Nord Stream pipeline explosions caused explosions as large as 100 kilograms of explosives.

A Swedish investigation found traces of explosives on several items recovered from the blast site.

The Wall Street Journal published a report in 2024 suggesting that a six-member Ukrainian sabotage team, including trained civilian divers, may have been responsible for the blasts.

The report alleges that Ukrainian President Volodymyr Zelensky initially approved the plan until the CIA found out about it and asked it to be stopped. However, his commander-in-chief at the time, Valery Zlozny, ordered him to move on. Keef has denied any involvement.

German media have since reported that Berlin asked Polish authorities to arrest a Ukrainian diving instructor who was allegedly part of a team that blew up the pipelines.

Although it is not impossible to get down to about 80 meters (260 feet) underwater, it would require significant diving skills, commented Salonius Pasternak, who had previously dived into the sea himself.

He explained that the seabed can be very unforgiving and cold, with poor visibility. “It’s not necessarily a place where you can suddenly jump out of a small boat and dive in and be successful with explosives.”

Anchor dragging, whether intentional or not, has been put forward as a theory for damage to cables between Finland and Estonia in 2023, as well as communication cables cut on Sunday and Monday.

How dangerous are these underwater events?

Very little.

Hare said all the affected countries have a high level of redundancy – additional or backup systems are available in case a cable or pipeline is damaged. As a result, there are very few disruptions to communications or energy supplies.

In the event of the latest cable bursting, the Nordic countries “could easily route their digital traffic along other fiber cables, without any reduction in services,” Hare said.

Salonius-Pasternak said the latest incident served as just one more reminder to NATO countries around the Baltic Sea that “redundancy is an important element of resilience”.

What good is underwater hybrid warfare if it poses little risk?

Creating anxiety and spreading fear.

Hare said that if nefarious elements are targeting NATO countries, their aim is to disrupt political and social harmony.

He said underwater sabotage, where even a powerful alliance like NATO struggles with “situational awareness”, could provide a “low-risk and accessible” tool to undermine social cohesion among member states. is