On 17 July 2025 Synopsys completed its acquisition of Ansys, a transaction its accounts value at US$34.86 billion, less than four months after Siemens had completed its acquisition of Altair. Both transactions moved major engineering-simulation portfolios between corporate owners. European rearmament depends on factories, skilled labour, test infrastructure, energetics, electronics and supply chains, but it also depends on a less visible industrial asset: the ability to reopen a design years after its original release, change it, analyse the consequences and produce engineering evidence that the responsible authority will accept. Modern aerospace programmes perform much of that work through commercial or jointly developed software environments for computer-aided design, product lifecycle management, structural and fluid analysis, systems modelling, optimisation and data exchange. The strategic question is therefore not whether a European programme owns its drawings or stores its files in Europe. It is whether the organisations responsible for the system retain, over decades, the legal permissions, executable software, engineering information, interfaces, competent personnel and validated processes required to turn those files into an approved design change. When the ownership of the tools changes, the question that remains open is whether that capacity changes with it.