A Ukrainian soldier is to go on trial in Hamburg accused of taking part in one of the most brazen acts of sabotage in postwar European history – the 2022 attack on the Nord Stream gas pipelines between Russia and Germany.

Serhii Kuznetsov, a special forces officer from the Ukrainian military, is accused by prosecutors of being an accomplice to war crimes by attacking civilian infrastructure, causing an explosion, damaging property and disrupting public services.

Kuznetsov, who will be identified in the trial opening on Wednesday just as Serhii K due to German privacy laws, was referenced by his full name in an extradition order. He is alleged to have prepared and carried out the detonation of at least four incendiary devices of up to 27kg in weight at a depth of about 80 metres under the Baltic Sea, close to the Danish island of Bornholm.

He is believed to have had six accomplices, including four deep-sea divers, an explosives expert and a ship’s captain, who are alleged to have used a rented yacht and timer-controlled explosives. Both he and his country deny any involvement in the attacks.

The explosions took place on 26 September 2022, badly damaging the pipelines which had been constructed to carry Russian natural gas between Vyborg in western Russia and Lubmin, near Greifswald in northern Germany.

The blasts caused the Nord Stream 1 pipelines – Russia’s main gas supply route to Germany before Moscow cut the supplies in August 2022 – to burst. They also damaged Nord Stream 2, which was ready to carry gas but was never put into operation after Germany suspended its authorisation process just before Russia’s full-scale invasion of Ukraine.

The attacks happened as European countries were seeking to transition away from Russian energy supplies in reaction to the Kremlin’s aggression.

They exposed the dependence of Europe – and, in particular, Germany – on Russian gas as well as highlighting the murkiness of underground operations during wartime.

Security observers initially blamed Moscow for the attack. Russia has denied involvement, in turn blaming the US, which has denied it just as forcefully.

However, in July German state prosecutors accused Ukrainian “state authorities” of ordering the attack, arguing: “The aim was to permanently halt gas supplies via the pipelines and prevent Russia from using the revenue from natural gas trade to finance its war effort.”

The Ukrainian president, Volodymyr Zelenskyy, has denied his country was involved.

Kuznetsov was arrested in August 2025 on a family holiday in Italy, with Italian police reporting that he surrendered without resistance. He had been travelling on a false passport. He was extradited to Germany last November, after legal efforts to prevent this failed.

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 fighting his extradition to Germany having applied for asylum in Croatia. He denies any role in the sabotage.

Aware of how potentially incendiary the trial could be, with Ukraine effectively in the dock for a crime committed against its ally – and one of its staunchest wartime supporters – the German government has declined to comment on the trial.

The far-right populist, pro-Kremlin Alternative für Deutschland party, which is soaring in the polls, has seized on the Nord Stream plot to boost its argument that German aid for Ukraine must cease and the pipeline be reinstated so that cheap supplies of gas can help counter the cost of living crisis.

The trial is attracting much attention, not least because Nord Stream was already a highly controversial issue before the attack, involving Russia’s leader, Vladimir Putin, who, with the then German chancellor, Gerhard Schröder, managed to bypass Ukraine as a transit country with Nord Stream 1. After Schröder left the chancellery, Putin appointed him as chair of the supervisory board of the company Nord Stream AG. Schröder was seen last week attending Putin’s birthday celebration.

A request by the Russians to participate as co-plaintiffs in the Hamburg trial was rejected by the court. The company Gazprom, which owns the Nord Stream 2 pipeline, had argued its right to do so due to what it has referred to as the severe economic consequences resulting from the attack. The court argued that while repair costs of the pipelines would be high, it would not be economically impossible to restore them.

According to reports, Kuznetsov, whose military ID indicates he was in active military service at the time the pipelines were blown up, is expected to maintain his right to remain silent during the trial.

His legal team is expected to produce affidavits from two of his military superiors to support the argument 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 who is considered to be the mastermind behind the attack and is one of those who has sworn in his favour.

Sixteen trial dates have been scheduled at Hamburg’s Hanseatic higher regional court up to and including 17 December, with further hearings likely in January and February.