The Most Dangerous Thing in Your Plant Is What You Can’t See Dale Peterson, founder and program chair of S4, threw down the gauntlet at this year’s S4x26 conference in Miami in February 2026 – demonstrate live industrial security in what was a first for the event. He tasked Booz Allen Hamilton to build a fully operational simulated automotive manufacturing environment with real Siemens and Rockwell Automation PLCs, a full SCADA layer running Ignition, and network segments representing a paint and assembly line. Eight security vendors were invited to solve real problems with live industrial equipment at the POC Pavilion. Cisco was one of them. The exercise underscored a truth that too many organizations still struggle to act on: you cannot secure what you cannot see. And in most OT environments, the gap between what operators assume is on their network and what is actually communicating across it remains dangerously wide. Complexity is the Enemy of OT Security Progress Industrial networks were previously not designed with cybersecurity in mind. They were designed to move product, maintain uptime, and keep people safe. Most OT environments have grown organically over decades, resulting in flat architectures where a paint booth controller can freely communicate with an assembly robot across the plant—or with a compromised workstation that was never supposed to be on that segment. Lateral movement across these unsegmented networks remains a leading concern. Yet many organizations remain stuck. The perceived cost of deploying OT security—specialized hardware, overlay architectures, and the risk of disrupting production—creates inertia. Patchwork approaches introduce their own friction, often requiring dedicated appliances and specialized staff that many do not have. Visibility First, Then Segmentation: A Phased Approach That Works The demonstration Cisco and Booz Allen jointly executed at S4x26 was built around a deliberately pragmatic premise: start with asset