Why Castelion, Why Now Castelion is moving incredibly fast to develop and deliver advanced defense systems at a time when execution matters more than ever. We believe focus and technical excellence are decisive advantages - and we are building a team that can deliver real capability, not just concepts. This is a rare opportunity to join at an early stage, where your work will directly shape critical systems, influence major technical decisions, and have immediate, real-world impact. Senior Manager, Classified Networks Administration Build, scale, and lead enterprise classified IT infrastructure across multiple secure facilities. Own strategy, architecture, deployment, and operations of classified network environments supporting mission-critical defense programs. Partner closely with Engineering, Cybersecurity, Facilities, Security, and Program Management to deliver compliant, resilient infrastructure in a fast-paced defense startup. Key

Responsibilities Define and execute enterprise classified network strategy across multiple sites, labs, and manufacturing facilities. Design, implement, and operate infrastructure supporting Secret, Top Secret, SCI, and SAP environments. Oversee networking, compute, virtualization, storage, identity management, monitoring, and disaster recovery. Ensure compliance with RMF, NIST 800-53, ICD 503, DISA STIGs, and Zero Trust principles; support ATOs and government accreditation activities. Drive infrastructure modernization through automation, Infrastructure as Code, and DevSecOps practices. Partner with engineering, program management, and executive leadership to align technology delivery with business growth. Manage infrastructure budgets, vendor relationships, and multi-year technology roadmaps. Recruit, develop, and retain high-performing technical talent across multiple locations. Support new facility stand-ups, classified program starts, and proposal activities. Required

Qualifications Bachelor's degree in Computer Science, IT, Engineering, or related field. 10+ years designing and operating enterprise infrastructure in classified environments. 5+ years leading technical teams across multiple sites. Experience in a defense contractor or government environment. Strong working knowledge of NIST SP 800-53, RMF, DoD cybersecurity policy, Windows Server/AD, Linux, VMware, Cisco networking, and enterprise storage. Demonstrated success building and scaling IT organizations in high-growth settings. Active Top Secret clearance; SCI eligibility required (CI Poly preferred). U.S. citizenship required. Preferred

Castelion is a modern defense production company building long-range hypersonic strike systems to address a critical national security gap. Founded in 2021, Castelion was created in response to the recognized need for the United States to rapidly develop hypersonic capabilities to remain competitive with near-peer adversaries and deter future conflicts.

The company operates under the philosophy of "Peace through Deterrence" — building the weapons systems that ensure conflicts never need to happen. Castelion is one of the few companies in the hypersonics space that has moved beyond concepts to actual production deliverables, with government contracts across multiple branches of the military and a $23M+ Navy order for 50 units in calendar year 2027.

Backed by over $469M in funding from top-tier investors including Andreessen Horowitz, Lightspeed Venture Partners, and General Catalyst, Castelion is scaling rapidly. The company is building what it anticipates will become the preeminent hypersonics campus in the country — including a $150M, 1,000-acre solid rocket motor manufacturing facility in Rio Rancho, New Mexico, alongside its headquarters in Torrance, California.

Castelion's culture is defined by technical excellence, ownership, and velocity. Engineers own meaningful subsystems on the vehicle and are responsible for driving their success. The company follows a responsible engineering model inspired by SpaceX, where individuals choose the highest-value work and are empowered to cultivate resources and partnerships to deliver results. The engineering bar is exceptionally high — attracting elite talent who want to be surrounded by other elite talent.

Senior Manager, Classified Networks Administration

About the role

About Castelion

Other roles at Castelion

Job details

Company

Funding

Founders

What happens next.

Confirm the fit

I pitch you to the company

A meeting lands on your calendar