Kelluu: from a North Karelia barn to NATO's exercise roster

Analysis as of 16 September 2025.

In the space of four months in 2025, a small Finnish airship maker appeared in two of the alliance's most visible test events. In June, an unmanned blimp built by Kelluu Oy flew within Atlantic Trident 25, the air-combat exercise that brought together American, British, French and Finnish forces — by the accounts cited in our research, the first occasion an autonomous lighter-than-air craft was folded into a drill of that scale. In September, the same platform travelled to Portugal for REPMUS 25, the multinational experimentation event for unmanned maritime systems, where it kept watch over a sea area under deliberately degraded satellite-navigation conditions. In 2025 the company was also picked from a field of more than 2,600 applicants for NATO's DIANA accelerator, standing among the fifteen firms carried into the programme's second phase.

The machine behind this run is deliberately modest. Kelluu's craft is a twelve-metre envelope lifted by hydrogen, able to stay aloft beyond twelve hours and to carry roughly six kilograms of interchangeable sensors — optical, thermal, multispectral, LiDAR. The company does not sell the aircraft. It sells the output: imagery and change-detection delivered through a cloud service, packaged as digital twins of whatever sits below the flight path. The design traces back to around 2016, when engineer Jouni Lintu began experimenting in a converted barn in rural North Karelia; the firm was incorporated in 2018 in Joensuu, with Jiri Jormakka as co-founder and Janne Hietala later arriving as chief executive. A first flight run entirely on hydrogen came in mid-2021, and in 2024 the company integrated into the propulsion PEM fuel-cell modules supplied by the UK's Intelligent Energy. A patented envelope structure that dispenses with conventional ballonets is what makes hydrogen — which can be produced in Europe, unlike imported and limited helium — a workable lifting gas.

Commercially, the anchor is civilian. Since 2023 Kelluu has flown recurring surveillance over Terrafame's sixty-square-kilometre mining and battery-chemicals complex under a multi-year service arrangement, through Finnish winters included. It has mapped national-park forests at centimetre resolution to trace bark-beetle damage, working with the Finnish Geospatial Research Institute and the University of Eastern Finland, partly under the Horizon Europe project RESDiNET. A second operating base opened in Sweden in 2023. The funding history mixes Finnish public money — Business Finland, regional funds, the state-linked impact investor Suomen Vaikuttavuussijoitus — with venture capital, and a Series A round was underway as of late 2023.

Why does a blimp matter to European defence finance? Because it sits in a coverage gap the continent has struggled to close with its own industry: persistent observation below cloud, cheaper than helicopters, longer-lasting than battery drones, higher-resolution than satellites — and built entirely inside the EU, at a moment when dependence on Chinese-made drones for infrastructure monitoring is treated as a liability. Our assessment places the system at TRL 7–8 and scores the company around 7 out of 10 on strategic autonomy: strong alignment with EU and NATO technology priorities, full domestic control of design and production, but a fleet still likely counted in single digits and no prime-contractor status. The next test is already scheduled — NATO's digital-backbone experimentation in Latvia in late 2025.

One question organises the whole report: what separates repeated exercise appearances from a first formal procurement by an armed force or an EU agency — and how close is Kelluu to crossing that line? Everything else bears on the answer. The foreign inputs that persist inside an ostensibly sovereign platform, American cameras and British fuel cells among them, and how readily European substitutes could replace them. Whether a single Joensuu factory and a fleet this small can scale to the demand its NATO exposure is generating. Where the patents and the in-house software actually place the company against rivals in lighter-than-air and pseudo-satellite surveillance. And which capability limits — endurance, payload, speed, deployment scale — still bound what these airships can credibly promise a buyer.