Europe’s ability to produce high-power radio-frequency amplification cannot be judged from the location of a prime contractor or from the existence of a nominally European product line. Travelling-wave tubes, which still amplify signals in satellites and ground stations where power and efficiency matter most, are built around a narrow set of specialised materials, electron-emission technologies, joining and vacuum techniques, high-voltage electronics, metrology, test equipment and qualification records. A production route can therefore remain physically present while becoming difficult to reproduce, modify or scale; conversely, the disappearance of one legal entity does not prove that its equipment, personnel or process knowledge have disappeared. Europe has already paid once to remove a specific dependency in this chain, through a Horizon 2020 project on export-restriction-free helix and support-rod materials, and has since seen one member of that project’s supplier cohort dissolve while others continued trading and the prime manufacturer moved into new frequency bands. For European rearmament, the relevant question is not whether Europe can point to a travelling-wave tube factory, but whether it retains controlled, qualified and replaceable industrial routes from specialist material and component sources through tube manufacture, power conditioning, integration and acceptance, and whether those routes survive once the public programme that created them has closed.