Architect and maintain ServiceNow security controls aligned to DoD Zero Trust architecture in FedRAMP High and DoD IL4/IL5 environments. Configure role-based access controls (RBAC), access control lists (ACLs), data policies, and edge encryption; maintain security matrices and enforce information-level segregation. Develop System Security Plans (SSPs) and Risk Management Framework (RMF) artifacts to support ATO attainment and sustainment. Conduct vulnerability assessments, continuous monitoring, manage Plans of Action and Milestones (POA&M), and generate security assessment reports.