HERSTAL, Belgium — One of Europe’s biggest air defense companies is warning that its top secret factories are being overflown by increasing numbers of drones, and it wants clear rules on how to jam or bring them down. “We are seeing more drones than what was the case a few months ago,” said Alain Quevrin, country director for Thales Belgium. He highlighted sightings over the company’s Évegnée Fort site in the eastern Liège region, the only Belgian facility where it is licensed to assemble and