We are seeking a highly motivated and detail-oriented Software Systems Engineer to support complex defense and government programs throughout the systems engineering lifecycle. The ideal candidate will have strong defense industry experience, expertise in requirements development and management, and hands-on experience with Model-Based Systems Engineering (MBSE) methodologies and tools including Cameo and Jama. This role requires collaboration with cross-functional engineering teams, program leadership, and government stakeholders to support system design, development, integration, verification, and delivery. Primary Responsibilities • Perform systems engineering activities across the full system lifecycle including: • Requirements analysis • Functional decomposition • System architecture development • Integration & Test • Verification & Validation (V&V) • Configuration management • Risk management • Develop, analyze, and maintain system engineering documentation including: • Program Interface Documents (PIDs) • Interface Control Documents (ICDs) • System/Subsystem Specifications (SSS) • Software Requirements Specifications (SRS) • Support requirements decomposition, allocation, traceability, and change management activities. • Utilize Jama for requirements management, traceability, and collaboration across engineering teams. • Utilize Cameo Systems Modeler to develop and maintain MBSE artifacts and system models. • Support requirements decomposition, allocation, traceability, and change management activities. • Develop SysML diagrams including • Activity diagrams • Sequence diagrams • Use case diagrams • Interface models • Support model-based architecture development and interface definition activities. • Conduct technical reviews, requirements reviews, and design reviews with internal teams. • Collaborate with software, hardware, cybersecurity, integration, and test teams to ensure system performance and compliance. • Provide technical leadership and support cross-functional collaboration across program teams. • Ensure engineering products comply with customer requirements, program objectives, and industry standards. • Participate in risk identification, mitigation planning, and technical issue resolution Required Qualifications • Be a US citizen with ability to obtain a security clearance • Bachelor's degree in Systems Engineering, Electrical Engineering, Computer Engineering, Software Engineering, or related technical field. • 4+ years of systems engineering experience or 2+ years with MS degree. • Prior experience supporting defense industry or Department of Defense (DoD) programs. • Hands-on MBSE experience using Cameo Systems Modeler. • Experience with model-based architecture development and SysML modeling. • Experience using Jama for requirements management and traceability. • Strong experience in requirements development and management. • Experience developing and maintaining: • Program Interface Documents (PIDs) • Interface Control Documents (ICDs) • System/Subsystem Specifications (SSS) • Software Requirements Specifications (SRS) • Experience with: • Requirements analysis • Functional decomposition • System architecture development • Verification & Validation (V&V) • Integration & Test • Configuration management • Risk management • Familiarity with Jira and Confluence collaboration tools. Original Posting: June 26, 2026 For U.S. Positions: While subject to change based on business needs, Leidos reasonably anticipates that this job requisition will remain open for at least 3 days with an anticipated close date of no earlier than 3 days after the original posting date as listed above. Pay Range: Pay Range $87,100.00 - $157,450.00 The Leidos pay range for this job level is a general guideline only and not a guarantee of compensation or salary. Additional factors considered in extending an offer include (but are not limited to) responsibilities of the job, education, experience, knowledge, skills, and abilities, as well as internal equity, alignment with market data, applicable bargaining agreement (if any), or other law.