The United Nations Permanent Peacekeeping Force is the Military organisation for the Terran Democratic Republic. The title may be somewhat misleading, as the UNPPF is an armed force in its own right, and does not just fulfil the role of "peacekeeper." Traditionalists prefer the name as it gives more of a civilised edge to the Terran military, elevating people's opinions about them.
The UNPPF is a military organisation in all respects, though. It is not responsible for scientific analysis of interesting space phenomena or exploring uncharted territory. The UNPPF is an army, nothing more.
Not overly large, the TDR fleet is sufficient to defend the planets of the Republic. Renowned across the galaxy for their fighters, the TDR has the largest proportion of carrier craft and fighter craft in the galaxy. Terran fighter pilots are amongst the most famous and highly praised in the known galaxy. However they do not compare to the sheer numbers of Gohorn vessels, so the TDR military spending has been stepped up in preparation for another war. Service to the military is voluntary.
Terran ships are functional, practical and aesthetically pleasing at the same time. At the outbreak of the Second Terran/Gohorn War, the UNPPF was not prepared for an offensive war. Only a few times during the 25th century had the UNPPF been required to fight, and so most of the crews were inexperienced with actual wartime combat.