The Royal Navy Space Service (RNSS) is the space-based branch of the United Kingdom's Royal Navy. Unlike other space-faring nations, the United Kingdom does not consider its space navy to be a separate service. As such, it maintains many of the traditions of the rest of the Royal Navy.
Within the UNSC's national naval forces, the RNSS is considered the second-largest national space fighting force, behind the United Republic Space Forces, with 109 ships, including five carriers and twelve arsenal ships, and 2,400 starfighters, and its ability to project power on an interstellar scale is considered third behind the UNSC Navy and the URNA Space Forces. Royal Marines are deployed on every RNSS vessel and can be deployed for ground operations at a moment's notice. The Space Service maintains 39,100 regular personnel with 3,600 volunteer support personnel, and 19,560 Regular Reserve.