Nukes, Leashes, and Navies

On September 17th, 2017, North Korea publicly detonated a hydrogen bomb as a weapons test. Given the general uselessness of radiation in space, as well as the lack of heat transfer, the general consensus was that space combat vessels would be armed with hydrogen warheads instead of regular fission warheads. While humanity, as far as they were aware, hadn’t yet mastered controlled nuclear fusion, the uncontrolled variety was much easier and plenty destructive enough to be used as a weapon against aliens.