Ukrainian troops tell CBS News why small, cheap drones are vital to the incursion into Russia's Kursk region

On the Ukraine-Russia border — CBS News met the troops of Ukraine's 117th Territorial Defense Brigade in the eastern Sumy region as they prepared for another trip to the front line. Their mission is to support Ukraine's military operations inside Russia's Kursk region.

The forces were preparing another drone for a one-way mission — its deadly payload: a grenade attached with cable ties. The simple weapon cost only about $400 to assemble, but it would soon be hunting multimillion-dollar targets.

Private Igor piloted the drone on a test run, but on real missions he can watch someone's final moments on his small screen, and he admitted that it can feel personal.