German prosecutors have announced the arrest in Croatia of a second Ukrainian suspect in connection with the 2022 Nord Stream pipeline explosions. The suspect is alleged to have been part of the diving team involved in placing explosives on the pipelines. The case remains politically explosive because the attack targeted critical European energy infrastructure during the war in Ukraine. It also raises difficult questions about state responsibility, European security and how governments should respond if wider involvement is established. For the public, the central issue is whether the full truth behind one of Europe’s most consequential acts of sabotage will ever emerge.