Microsoft and Nvidia separately announced strategies positioning AI as an active participant in enterprise cyber defense, moving beyond protecting models from prompt injection, unauthorized access, and data exposure. Microsoft introduced "Project Perception," an agentic security platform built around a "Cyber Stack" designed to "continuously perceive, reason, and act," coordinating specialized AI agents to identify vulnerabilities, investigate threats, and strengthen defenses while keeping humans in control. Hayete Gallot, executive vice president of Microsoft Security, wrote, "The physics of cybersecurity are changing," adding that approaches built for human actors cannot keep pace with AI and machine-speed attacks. The platform is a continuously learning system using broad security telemetry, contextual reasoning, multiple AI models, specialized agents, and "actuators" that translate recommendations into protective actions. The same day, Nvidia unveiled the Open Secure AI Alliance, a coalition of technology companies and open source organizations aiming to develop and share AI security models, evaluation harnesses, and defensive tools. Nvidia framed openness as a security advantage, stating that the United States and its partners face a choice between defenses inside a few opaque systems or open models, harnesses, and tools any defender can study, adapt, and deploy. The alliance builds on the Linux Foundation's Akrites initiative and the OpenSSF community, with founding participants including Microsoft, IBM, Cisco, CrowdStrike, Hugging Face, Palantir, Red Hat, Siemens, SAP, Naver, and SpaceXAI. The strategies