The United Nations Navy (UNN) is the naval branch of the United Nations (UN) military. It is considered less technologically advanced than the Martian Congressional Republic Navy (MCRN). However, it has the largest fleet in the Solar System and is generally considered to be the overall superior of the two.
Earth’s military, primarily the United Nations Navy (UNN) and the United Nations Marine Corps (UNMC), are arguably the most powerful combined military force in the system. Most of the UNN is spread throughout the Solar System, overseeing and protecting Earth's interests in the Belt and the Outer Planets or keeping the peace as part of the Earth-Mars Coalition Navy.
While not as technologically advanced as the MCRN, the United Nations Navy is considerably larger, consisting of capital ships such as Dreadnoughts and Battleships, as well as smaller vessels like Cruisers, Destroyers, Frigates, Corvettes, Patrol Torpedo boats, and Fleet support ships. Nevertheless, projections have shown that the technological superiority of Mars would give them an edge against UNN numbers in any major conflict between the two planets. unless the UNN can mobilize an overwhelmingly large force. This is due to many of UNN ship designs being outdated or even obsolete, with aging or substandard weaponry the likes of which are often vastly outranged by those of the MCRN. The United Nations Marine Corps serves aboard UNN vessels and guards UN outposts in the Belt and beyond. Marines wear vacuum-rated and radiation shielded Reaver powered armor, enabling them to engage in combat operations virtually anywhere in the system. The UNMC can place over 100 million troops on the battlefield at a given time, far outnumbering the ground forces of any other nation including Mars, and the fact that UN marines are born, raised, live, and train in the full gravity of Earth, gives them a considerable advantage against opponents accustomed to the lower gravity of Mars or the Belt.