European naval rearmament is normally measured at the level of hulls, weapons, sensors, combat systems and prime contractors. That perspective is incomplete for survivability capabilities whose effectiveness depends on specialist engineering performed well below the platform level. Electromagnetic signature management is one such case. A warship may retain its hull, its propulsion and its principal combat system while its ability to control, measure and interpret aspects of its underwater electromagnetic signature depends on a small population of engineers, on dedicated power electronics and sensors, on software, on vessel-specific data accumulated over years of ranging, and on access to test and qualification processes that are not themselves commercial products. Polyamp Aktiebolag, a Swedish company of twenty-one people, is a useful test of how such dependence should be assessed, because during 2026 its governance changed, a new holding vehicle appeared beside it, and its financial statements recorded a distribution large enough to alter the picture of its resilience. The question is not whether a small Swedish specialist is important in some general sense. It is whether European naval customers can preserve the legal rights, the technical knowledge, the industrial processes and the financial continuity required to sustain and modify a capability if ownership, personnel, supply conditions or contractual relationships change — and whether, if they cannot, an alternative exists that could be qualified within the time a navy has.