This month’s summits between America, Russia and Europe haves produced no concrete agreements on ending Ukraine’s war. On land, Ukrainian forces are limiting Russian advances on the eastern front to a slow, bloody crawl. At sea too, it is up to Ukraine’s drones, missiles and small boats to keep the Russians out.

Russia launched drones and a missile into Ukraine overnight into Sunday, the air force in Kyiv said, as the country kicked off independence day celebrations marking the anniversary of its 1991 declaration of independence from the Soviet Union.

As Ukraine pushes a shock incursion into Russia, a drone unit tasked with supporting the mission tells CBS News why the inexpensive weapons are so vital.