Robust multi-level security (MLS) and compartmented security cross domain solutions (CDS) are necessary to achieve the Distributed Mission Operations (DMO) vision to have warfighters train as they fight. This paper describes achievements and challenges for a Distributed Mission Operations Network (DMON) cross domain production capability to be implemented in December 2006. This paper addresses the key technical and policy challenges for a guard-based CDS implementation. There are significant steps required for a new simulation guard application to achieve Protection Level 3 security certification and accreditation (C&A) in accordance with Joint Air Force, Army Navy (JAFAN) 6/3 security guidance. This paper describes the processes performed, the technical and policy achievement applying lessons learned for guard implementation and the associated certification and accreditation activities.