Senior ISSE - Lead Security Architecture (TS/SCI)

Agentic Defense Solutions, Inc.; Tysons (VA); On-site; USD 150,000 - 230,000; Full time

Job summary

Agentic Defense Solutions, Inc. is hiring a Principal Information Systems Security Engineer to act as the senior technical authority for security across mission systems at multiple classification levels.

You will own security architecture from concept through accreditation and sustainment, translating policy into buildable requirements and serving as the main technical interface to AO, SCA, and ISSM staff. You will lead the technical direction, defend risk positions in architecture reviews, and

Qualifications

• Active TS/SCI with Full Scope Polygraph.
• 15+ years of relevant security engineering experience.
• 10+ years in a classified environment.
• Ownership of at least three systems through full ATO.
• Deep knowledge of NIST SP 800-53, NIST RMF (SP 800-37), CNSSI 1253, ICD 503, and DISA STIG/SRG.
• Hands-on depth in two or more: Linux hardening, network security, IAM, cloud security, or cryptographic key management.
• Ability to communicate technical risk clearly to government stakeholders and write accreditation documentation.

Responsibilities

• Lead security architecture and design for mission systems across on‑premises enclaves, air‑gapped environments, and cloud regions.
• Own the full RMF/ATO lifecycle including evidence artifacts (SSP, SAR, POA&M) and risk assessments.
• Interface with AO, SCA, ISSM and customer stakeholders; present risk positions and tailoring rationale.
• Perform threat modeling and security reviews; document residual risk and mitigations.
• Audit control implementations against NIST SP 800-53, CNSSI 1253, DISA STIGs; drive automated compliance.
• Lead responses to assessments, vulnerabilities, and incidents; conduct root‑cause analysis and durable fixes.
• Mentor junior ISSEs and engineers; establish reusable patterns and engineering standards.
• Support capture and proposals as a security SME and solution architecture contributor.

Skills

TS/SCI clearance

Full Scope Polygraph

Senior security engineering

Risk communication

Tools

NIST RMF

NIST SP 800-53

CNSSI 1253

DISA STIG/SRG

Job description

Agentic Defense Solutions, Inc. is hiring a Principal Information Systems Security Engineer to act as the senior technical authority for security across mission systems at multiple classification levels.

You will own security architecture from concept through accreditation and sustainment, translating policy into buildable requirements and serving as the main technical interface to AO, SCA, and ISSM staff. You will lead the technical direction, defend risk positions in architecture reviews, and