Ukrainian soldiers with the 1st Independent Center for Unmanned Systems ready a Fire Point FP-1 drone for an attack mission.

Giorgos Moutafis/Business Insider

DNIPRO, Ukraine — There is an eerie silence in the middle of the night in a field in eastern Ukraine as Ukrainian soldiers prepare drones to strike inside Russia hours later. They have laid out the drones — FP-1 models loaded with explosives that look more like small propeller planes. Then the launch begins.The whole world is talking about the soldiers here, waging the drone war by flashlight. In recent months, they have helped turn Russia's war of aggression against Ukraine to Moscow's disadvantage. They are giving Ukrainians hope again by striking oil and gas facilities inside Russia and carrying the war back to the country that started it.BILD, a partner in the Axel Springer Global Reporters Network that includes Business Insider, spent one night with the Ukrainian unit known as the "1st Independent Center for Unmanned Systems," which operates under the strictest secrecy.Total secrecyThe drone attack was supposed to happen much earlier. Then we get the call: Everything is being pushed back. It is shortly before midnight when we leave the major city of Dnipro and head farther east, toward the front. Ukrainian soldiers drive ahead. We stop at a gas station that has already been attacked. "Guys, don't smoke here — we only have one pump left," says a woman who is also waiting there in the middle of the night.On every mission, the unit's biggest fear is being discovered. We have to switch off and hand over all our smartphones. One thing is clear: If Russian reconnaissance picked up what the soldiers were planning, there would probably be an immediate drone strike. But Ukraine is vast, and the soldiers go to great lengths not to attract attention.The mission begins