Russian troop build-up threatens city seen as key to seizing Ukraine's Donbas

That appears to explain the Kremlin's decision to surround and seize Kostyantynivka as quickly as possible. The situation has become a "major crisis", the Ukrainian drone pilot warns. Russian drone units do not even need to rely on sophisticated unmanned systems as they are now close enough to use cheap Chinese drones that cannot fly far to conduct surveillance and identify Ukrainian drone launch sites. Delivering supplies has become extremely difficult, with land routes constantly targeted and big logistical drones regularly intercepted. The fall of Kostyantynivka "is a matter of time", says Ukrainian frontline monitoring project DeepState. Once that happens, logistical operations in the area will be more complicated and even remaining in Kramatorsk will become "extremely dangerous", it reports. Another Ukrainian soldier whose unit is fighting in the city has said they are not getting the necessary reinforcements to cover their losses, and their commanders are reluctant to report about lost positions. If they do, then they will be ordered to retake them: "We don't have enough people to hold on to what we still control, let alone organise assaults." "We are still fighting inside the city," the drone pilot says, "But unless we change our approach and start destroying their logistics and targeting their pilots, they will continue advancing."