After finishing the Naval Academy in 2000, LTC Kos started his career in the Navy as Bridge Officer on various RNLN ships. Returning to the Royal Military Academy till 2002 to finish his studies in Business Administration, after which he switched to the Air Force to become an Officer within the Logistics Corps and specialized in Operational Logistics and Movements. After various posts, including a tour as LNO assigned to USEUCOM for operations into Afghanistan, he was transferred to Papa Airbase Hungary to become Air Movements Officer for the Heavy Airlift Wing (HAW) 2009-2012. From 2015 till 2021 LTC Kos was assigned to the NLD NMCC (National Movement Coordination Centre) as Project Officer Strategic Movements Planning and Execution. In this role he was responsible for the planning and execution of some of the strategic movement of NLD Units across the world for exercises and operations. One of the largest exercises being the NATO Trident Juncture 2018 exercise into Norway, where he led the NLD forward NMCC element in Norway. He was the primary NSPOC (National Single POC) for Movement of US forces moving in and out of the European Theatre under the Defender and Atlantic Resolve cycles, through NLD as one to the main Transit Nations. He dealt with 21TSC and USAREUR and linked them as Sending Nation to NLD-BEL-DEU and POL to create a coherent integrated movement plan, using best practices of all involved. After this assignment LTC Kos was transferred to the NATO Standing Joint Logistic Support Group (SJLSG) which, one year in existence, was subsumed by the NATO Joint Support & Enabling Command (JSEC), both situated in Ulm Germany. Here he was posted in a J5 Operational Logistics Planner position, during the development of the new Family of Plans period within NATO, which lead to the Regional Plans development we know today. As a SJLSG LNO he was deployed to Joint Forces Command Naples (JFCNP) during Operation Allied Solace, the evacuation of Kabul in which he performed the SJLSG task to quickly assemble all involved NATO Nations in a coherent manner under the established JTF commander (after Naples was assigned this task). Beginning of 2023 LTC Kos was assigned to the DNO Office (German Netherlands Office) on Military Mobility also located in Ulm.