The Silent Layer of Air Defence: Why Passive Infra-Red Sensors Are Becoming Harder to Ignore

Passive infra-red and electro-optical sensors are becoming one of the least understood layers of modern air defence. They do not replace radar, but they can help air-defence networks detect, track and classify aerial threats without transmitting radar energy. This makes them harder to detect electronically and harder to suppress in contested airspace. From Israel’s Sky Spotter to European, US, Russian, Chinese and Iranian systems, passive EO/IR sensing is moving from a specialist technical niche into the centre of modern layered air defence.