Stefan Thumann

Stefan Thumann is the founder, chief executive and chief designer of Donaustahl, a small manufacturer at Hutthurm in Lower Bavaria that builds loitering munitions, the avionics that fly them and the warheads they carry. He holds all three roles, which is a fair description of the company: it is an engineering shop organised around one person’s design decisions rather than a firm with a design department.

His stated approach is a rejection of how the established European defence industry works. He has summarised the ambition as not wanting projects in a drawer, but products in a warehouse, and the company markets itself as “offense-tech” — a deliberate contrast with the defensive framing most European suppliers prefer.

The design that made the company known reflects the same instinct. The ALMP Maus is an adaptive loitering munition whose airframe is made from specially treated wood rather than carbon fibre, which Donaustahl says cuts frame production cost by roughly 75%. The platform carries a 2.7 kg payload to an effective five to seven kilometres, climbs at 18 to 22 metres per second, and flies at night on infrared. The warhead is interchangeable between shaped charge, fragmentation and anti-materiel fits. The companion Combat Stack avionics are built to be assembled without soldering, which is a decision about who will be doing the assembling and where.

In July 2024 Germany’s economics ministry granted Donaustahl an export licence for the Maus under conditions, and the first deliveries went to Kraken, a special unit under Ukraine’s Main Directorate of Intelligence. The company has said it shipped a double-digit number of the platforms along with quick-release and ignition systems for PG-7 warheads. A German firm cleared to export a weapon system directly to a Ukrainian intelligence formation is unusual, and it made Thumann a publicly identified figure in a way most defence engineers are not.

In December 2025 he was warned that Russia was planning to have him killed. He has lived in hiding since, moving location every few weeks under constant protection, and has given interviews from undisclosed locations. Two people described as low-level agents have been arrested. Bavaria’s interior ministry has confirmed it is aware of the case and declined to comment further while federal prosecutors investigate. Nothing has been established in court, and no Russian official has been charged in connection with ordering it.

Thumann is the clearest European example of a pattern this site tracks: a very small engineering firm producing a fielded weapon on a timescale the large primes do not attempt, and doing it by giving up things the primes will not — carbon fibre for treated wood, a polished supply chain for solder-free assembly near the front. The Maus is a design argument about cost per shot rather than performance per unit.

He is also a study in what public identification costs. Being the named face of a German firm exporting munitions to Ukrainian intelligence is precisely what made the company credible and, on the available reporting, precisely what put him in hiding.