Mysterious drones keep buzzing key sites in Europe. So what's the defence strategy?

https://www.cbc.ca/news/world/drones-belgium-europe-russia-9.6973910

Even before at least three drones were reportedly spotted over a power plant in northern Belgium on Sunday evening, Brussels was on high alert.

A rash of drone sightings has led to repeated airport closures in the country, stranding thousands of passengers and grounding planes.

Belgium is the latest target in a string of mysterious drone incidents across Europe over airports and military sites — and some officials have directly pointed the finger at Russia. It has left authorities scrambling to boost defences.