The latest U.S. push to end Russia’s nearly 4-year-old war in Ukraine has unleashed a frenzy of diplomatic activity.

In a disused warehouse at an undisclosed location in Ukraine, a military drone instructor who goes by the call sign "DC" showed CBS News a makeshift practice course that students must learn to fly the increasingly indispensable devices through before they join the country's defense against Russia.

By maintaining stability and innovating to hold out against Russia, Kyiv has shown that size matters less in conflict than it used to

On Tuesday, Russian President Vladimir Putin declared that Russia had taken the Ukrainian town of Pokrovsk, marking the culmination of a 20-month campaign. Ukraine denied the town had fallen, saying that its troops were still in control of the north.

Early Ukrainian military recruitment ads were a call to arms in an existential fight. Now, they frame joining as cool, a good career move or a point of pride.