On the weekend, Denmark reported unidentified drones had appeared above its major military bases. It was the country’s third drone alarm in a week and one of five European nations in a month to experience incursions - from either drones suspected of Russian origin or from the Russian Air Force itself.

So why is Russia violating Europe’s skies, seemingly with impunity?

Political and international editor Peter Hartcher says it’s all part of a "hybrid war", and one that Australia is no stranger to. And, Hartcher argues, the West has been blind to these attacks.