A Ukrainian former military officer, identified only as Serhii K., is on trial in Germany accused of orchestrating the 2022 sabotage of the Nord Stream gas pipelines. The case opened Wednesday at the Hamburg Higher Regional Court and is expected to run until February next year, with prosecutors presenting the first public hearing of evidence in a years-long investigation. Prosecutors allege the 50-year-old led a group of Ukrainian agents, including divers and an explosives expert, in one of the biggest infrastructure sabotage operations in modern times. They say he worked with other members of the military to plan the operation on behalf of unidentified Ukrainian state entities. Prosecutors accuse Serhii K. of travelling to Germany through Poland on a forged Ukrainian passport about three weeks before the attack. The group, they allege, used a sailboat hired in Rostock to reach an area near the Danish island of Bornholm, where they attached military-grade explosives with timers to the pipelines on the seabed. German prosecutors say the sabotage targeted civilian infrastructure and would amount to a war crime. On September 26, 2022, Swedish seismologists detected multiple blasts, some 17 hours apart, and three of the four concrete-coated steel pipelines ruptured, sending huge plumes of methane into the atmosphere. Nord Stream 1 supplied about half of Germany’s natural gas imports. Nord Stream 2 was built but never opened after Berlin cancelled approval shortly before Russia invaded Ukraine. Serhii K. was arrested in Italy in August 2025 and extradited to Germany in November. Another suspect, Vladimir Z., a trained scuba diver prosecutors say was one of the divers on the team, was arrested in Croatia in August, and a Croatian court approved handing him over to Germany last month. The trial is ongoing at Hamburg Higher Regional Court, with prosecutors seeking accountability through public hearings that continue into February.