At a secret location in rural Ukraine, columns of attack drones are assembled at night and in near silence to strike deep inside Russia. Since the summer, Ukraine’s long-range drone campaign has ramped up dramatically, pounding energy infrastructure across Russia and stretching Moscow’s air defenses thin.

In previous sieges during the almost four years since Russia launched its all-out invasion of its neighbor, Ukraine has pulled out of some places to avoid losing troops. Ukrainian forces are desperately short-handed against Russia’s bigger army.