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