Kelluu began, as startups often do, in an old shed.
The small Finnish company makes airships — think van-sized blimps — originally designed to watch over power lines with cameras.
When I met the firm’s CEO, Janne Hietala, last fall, he arrived at our restaurant in Joensuu with news. Kelluu, a seven-year-old company, had just become a defense contractor.
A NATO member had agreed to buy airships for surveillance under an alliance program pushing Western militaries to adopt new tech. The buyer hasn’t been named, but it plans to integrate the airships into its military within two years.
Kelluu’s ascent was just as rapid. The company’s first showcase to NATO, Hietala said, was in November 2024.
Kelluu is trying to make it big in a market that hasn’t been kind to small firms. Traditionally, Western nations have depended on giant contractors that meticulously take decades to create and fine-tune systems. These firms, often referred to as the “primes,” had all of the contacts and, by extension, all the business.
But now, the door is opening for founders from the commercial world.
Events in the last few years — the invasion of Ukraine, the second Trump administration, and the rise of drone warfare — have jolted NATO militaries, who now fear an overreliance on the primes. European generals and politicians alike agree: To convince Russia that it would lose a war, the continent needs a steady stream of ammo and equipment that can be quickly designed, tweaked, and produced in large quantities.
“It’s no longer possible to just adhere to the old pace of months and years of planning, months or years of procurement, months or years of development,” a spokesperson for Defence Innovation Accelerator for the North Atlantic, or DIANA, the NATO agency that connected Kelluu with alliance members, told me.
NATO conceptualized DIANA before Russia invaded Ukraine in 2022, as a program for emerging firms to present their tech to allied militaries and potentially sign contracts. Following the outbreak of the war, the agency was established in 2023.
The agency said it received 4,000 applications for its next cohort, up from 2,400 last year and 1,200 in its inaugural batch in 2023. At least half of these firms and founders are from Europe.
Investors who once viewed the defense sector as taboo are scouring the industry. According to the NATO Innovation Fund in February, venture capital investments in European defense tech reached $1 billion in 2024, up by four times since 2020.
I traveled in the fall of 2025 to northern Europe, where concerns about war with Russia run high, to speak with defense startups finding their corner of a market that was closed to them five years ago. To make it in the old defense world, small firms typically needed to be bought by a prime.
With that barrier fading, the founders I spoke to have set their ambitions high. The European Union has a new goal of allocating $920 billion more to defense by 2030, and NATO members are raising their commitment to spending 5% of GDP on their militaries.
“No wonder that even the US investors are now looking at the European landscape, which wasn’t a thing a year ago,” Hietala said.
Read this collection to get to know some of the startups seeking a slice of Europe’s expanding war chest:
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