Hamburg’s Hanseatic higher regional court opened proceedings on Wednesday against a Ukrainian special forces officer accused of helping orchestrate the 2022 sabotage of the Nord Stream gas pipelines, placing questions of state responsibility, prosecutorial authority and wartime accountability at the centre of one of postwar Europe’s most consequential criminal trials.
The defendant, identified under German privacy law as Serhii K but named in full in an extradition order as Serhii Kuznetsov, faces charges of being an accomplice to war crimes through the attack on civilian infrastructure, causing an explosion, damaging property and disrupting public services. Prosecutors allege he prepared and carried out the detonation of at least four incendiary devices, each weighing up to 27kg, at a depth of roughly 80 metres under the Baltic Sea near the Danish island of Bornholm.
The charges rest on the claim that Kuznetsov acted with six accomplices: four deep-sea divers, an explosives expert and a ship’s captain, using a rented yacht and timer-controlled explosives. Both the officer and the Ukrainian state deny any involvement.
The explosions took place on 26 September 2022, badly damaging pipelines built to carry Russian natural gas between Vyborg in western Russia and Lubmin, near Greifswald in northern Germany. Nord Stream 1, Russia’s main gas supply route to Germany before Moscow cut supplies in August 2022, burst in the blasts. Nord Stream 2, ready to carry gas but never put into operation after Germany suspended its authorisation process shortly before Russia’s full-scale invasion of Ukraine, was also damaged.
The case has moved through several jurisdictions before reaching Hamburg. Kuznetsov was arrested in August 2025 while on a family holiday in Italy, where Italian police reported that he surrendered without resistance. He had been travelling on a false passport. After legal efforts to block his removal failed, he was extradited to Germany last November. A further suspect, Volodymyr Zhuravlyov, an air conditioner installer and hobby diver, was arrested on a European warrant in northern Croatia in August. He is contesting his extradition, has applied for asylum in Croatia, and denies any role in the sabotage.
The prosecutorial theory carries significant diplomatic weight. In July, German state prosecutors accused Ukrainian “state authorities” of ordering the attack, arguing the aim was to permanently halt gas supplies through the pipelines and prevent Russia from using natural gas revenue to finance its war effort. Volodymyr Zelenskyy, the Ukrainian president, has denied his country was involved. Security observers initially blamed Moscow, which has denied involvement and in turn blamed the United States, a claim Washington has rejected just as forcefully.
The court itself has already made one notable ruling on who may participate. A Russian request to join the trial as co-plaintiffs was rejected. Gazprom, which owns the Nord Stream 2 pipeline, had argued for that right on the basis of what it described as severe economic consequences from the attack. The court reasoned that although repair costs would be high, restoring the pipelines would not be economically impossible.
By contrast, the German government has declined to comment on the proceedings at all, aware of how politically charged a trial could become with Ukraine effectively in the dock over a crime committed against one of its staunchest wartime supporters. The far-right, pro-Kremlin Alternative für Deutschland party, which is rising in the polls, has seized on the case to argue that German aid for Ukraine must cease and the pipeline be reinstated so that cheap gas can help counter the cost of living crisis.
The trial also reopens a contested chapter of German energy policy. Nord Stream was controversial well before the attack, involving Russia’s leader, Vladimir Putin, who together with the then chancellor, Gerhard Schröder, bypassed Ukraine as a transit country with Nord Stream 1. After leaving the chancellery, Putin appointed Schröder chair of the supervisory board of Nord Stream AG. Schröder was seen last week attending Putin’s birthday celebration.
According to reports, Kuznetsov’s military ID indicates he was in active service at the time the pipelines were blown up, and he is expected to exercise his right to remain silent. His legal team is expected to submit affidavits from two military superiors arguing that he is prohibited from revealing details of his actions as a soldier. He is reported to have allegedly taken his orders from a man considered the mastermind of the attack, who is among those who have sworn in his favour.
Sixteen trial dates have been scheduled in Hamburg up to and including 17 December, with further hearings likely in January and February. Whether the court can resolve the question of state responsibility while the defendant stays silent remains the trial’s central open question.