A Hacker News discussion centers on a cyberattack that halted construction of the Fehmarnbelt tunnel linking Denmark and Germany—one of Europe’s largest infrastructure projects. Danish digital security officials warn of possible Russian hybrid warfare amid raised threat levels. Commenters argue critical physical systems should be unplugged from the internet or air-gapped, though air-gapping isn’t foolproof. Others warn AI will exponentially increase attacks, exploiting legacy firmware and poorly secured industrial systems, and predict consolidation and AI-driven defenses. Some see the incident as part of broader hybrid attacks, citing recent disruptions like supermarket fridge defrosting and retail outages. The thread also debates centralization of cloud/data centers, redundancy, geopolitical escalation, and whether blame is being assigned too quickly. Several note decades of insecure software and urge serious hardening of critical infrastructure. The overall tone: expect more such disruptions, and unplugging may become the safer cost-benefit choice.