Leidos is seeking a skilled Senior Trellix/Microsoft Defender Administrator in Fort Belvoir, VA to join the I3TS team supporting DTRA. The I3TS program provides enterprise-wide IT support to enable DTRA's Information Management & Technology Directorate (ITD) to consolidate, modernize, and continuously innovate the delivery of IT services and mission capabilities to DTRA's internal and external mission partners operating in CONUS and OCONUS locations. The candidate will be responsible for ensuring the security and integrity of IT systems by running their Endpoint Security with experience in Trellix and Microsoft Defender. Administrator will also be responsible in applying Security Technical Implementation Guides (STIGs), managing system patches, and overseeing vulnerability management processes. This role supports federal clients in maintaining compliance with the Department of Defense (DoD) and other federal cybersecurity standards. The candidate will be responsible for identifying points of vulnerability, non-compliance with established Information Assurance (IA) guidelines and regulations and recommend mitigation strategies, along with assisting users as needed in a classified computing environment. The selected candidate must be able to work independently as well as with a team of IT analysts, administrators, and engineers. The position requires excellent communications skills, both verbal and written. The candidate must be able to work in a high-energy environment and adapt to shifting priorities.