Who blew up the Nord Stream pipelines? Germany’s sabotage trial reopens Europe’s biggest energy mystery years after the Baltic Sea explosions

Four years after explosions damaged the Nord Stream gas pipelines beneath the Baltic Sea, Germany’s attempt to establish individual responsibility has reached a courtroom. The trial of an ex-Ukrainian military officer started in Hamburg on Wednesday, putting the focus once again on one of the most significant acts of suspected sabotage of infrastructure in Europe.

The explosion in September 2022 damaged three out of four pipelines through which Russia supplies gas to Germany.

At first, investigators were faced with competing explanations regarding who the perpetrators were, but German prosecutors claim that Ukrainian citizen Serhii Kuznietsov participated in organising the crime.


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According to CNN reporting on the trial, the suspect denies his guilt, while Ukraine denies state involvement. The trial can provide information regarding how the crime was committed and who might have participated in it.

Moreover, the trial raises a delicate issue for Europe: how to deal with Germany’s accountability for actions that involve Ukraine, Germany's ally during the Russian invasion?

What happened to the Nord Stream pipelines in 2022?

Nord Stream 1 and Nord Stream 2 were conceived for the delivery of Russian gas straight to Germany through the Baltic Sea.

The two pipelines faced criticism even before the explosions due to the claim that the construction would enhance Europe’s reliance on Russian energy sources and decrease the role of Ukraine as a gas transit state.

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Construction of Nord Stream 1 took place in 2011. The second pipeline was completed by September 2021 but was not commissioned into use. Germany halted the approval process in February 2022 just before the full invasion of Ukraine.

In September 2022, explosions occurred underwater, damaging both pipelines in the proximity of the Danish island of Bornholm. Natural gas poured into the sea, forming bubbles at the water surface.

As CNN reported, the blasts were considered immediately to be a possible case of sabotage rather than a mere technical problem. Swedish authorities found explosives at the site, and European politicians criticised the attack on vital infrastructure.

The explosions happened in a moment of great conflict between Russia and the West due to energy supplies. The Russian government had already decreased gas supplies to Europe, and the damage made Germany’s energy position more difficult.

Who is the Ukrainian suspect, and what do prosecutors allege?

Former Ukrainian special forces officer Kuznietsov stands accused of being part of the group which planted explosives on the pipelines.

As the German prosecutors have claimed, the plan included several people, such as divers and an explosives specialist who used a rented sailing yacht for their activities.

The prosecutors allege that the yacht was rented through intermediaries with false identity papers, and the people managed to plant explosive devices on the pipelines located in the Baltic Sea area of Bornholm.

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He faces charges in connection with causing explosions, damaging property, interference with public utilities, and war crimes as an outcome of an attack on civilian infrastructure. Kuznietsov was detained in Italy in August 2025 before his extradition to Germany.

CNN earlier mentioned the international warrant and investigation regarding Kuznietsov’s involvement.

At the opening of the trial, his defence challenged the case and argued that the pipelines could be considered legitimate military targets because of their connection to Russia’s war effort.

Questions were also raised regarding his duty as an active soldier in the Ukrainian army to safeguard military information. According to Reuters, the defence argued for the dismissal of the case, whereas the prosecution believes that it was a criminal act.

This is a conflicting legal interpretation, not a proven one. The trial must examine the evidence before the court can determine the defendant’s responsibility.

Why the investigation became a diplomatic problem for Europe

The investigation has taken on significance beyond the question of who physically planted the explosives.

If prosecutors establish that the operation involved Ukrainian personnel, questions could follow about whether the alleged participants acted independently or on instructions from officials.

The German prosecutors have also accused the Ukrainian government of being behind the attack. The Ukrainian president, Volodymyr Zelensky, says that the allegations are not proof of any decision by the Ukrainian government.

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This incident is especially sensitive to Germany because Germany has been one of Ukraine’s important supporters in Europe.

Pursuing criminal accountability is a matter for German authorities, but the proceedings could become politically contentious if evidence raises questions about the involvement of people connected to Ukraine’s military or security services.

The investigation has also narrowed over time. Both Sweden and Denmark have finished their investigation in 2024, and only Germany continues with its own investigation into the crime.

As per CNN's report on the incident, the initial investigation involved various countries, while the international arrest warrant involving the Ukrainian suspect was released in 2024 through Germany.

Another citizen of Ukraine named Volodymyr Zhuravlov has also been arrested with regard to the case.

His legal proceedings have involved a separate extradition process, meaning the German trial of Kuznietsov does not by itself resolve every question about the alleged operation.

What the Nord Stream trial could reveal about Europe’s energy security

This is another instance of how fragile such infrastructures can be when they run across international boundaries and are located deep beneath the oceans.

Such infrastructure is hard to monitor all the time, especially when it extends through international waters belonging to multiple states.

The explosions in the Nord Stream have further revealed the politics involved in the dependence of Europe on Russian sources of energy. Before the invasion of Ukraine, these pipelines had been a key part of Germany’s natural gas plan.

The trial will presumably last for many months to come, with further sessions taking place even during winter.

Perhaps the most significant findings of the trial will lie in the connection of the accused with the operation and the question of what exactly other members of the group did, as well as what legal consequences there can be when attacking critical infrastructure in wartime.