(ANSA) - BELGRADE, OCT 8 - "The Drone Wall represents our response to the realities of modern warfare. Think of what happened in Poland. We had to use very expensive systems, such as latest-generation fighter jets, to shoot down relatively inexpensive, mass-produced weapons. This is not sustainable," Ursula von der Leyen stated this during the plenary debate on a unified response to Russia's recent violations of European airspace. (ANSA).