“Fire!” he shouts, and pulls the cord. A deafening explosion shakes the armoured machine.
They fire just one round, and then wait for the next command.
But after a prolonged silence, the same crackling voice on the radio gives them an order: “Stand down and cover the gun.”
Ukraine’s gunners have to use ammunition rounds sparingly, as there is a shortage of artillery shells.
Their gun, like most artillery systems provided by the West, fires 155-mm projectiles that are also supplied by foreign partners.
The problem is, Ukraine’s troops need more rounds than their allies can currently give them.
Without ammunition, Ukraine won’t just have to stop trying to recapture land: it won’t be able to stop Russia’s attacks and could ultimately lose this war.
“Right now, the enemy is trying to break through [our defence lines]. Each day, there are at least two attacks, but we repel them all,” says Igor, a platoon commander from the 93rd Brigade. His crew has been on watch since 05:00.
Igor’s unit defends areas near the eastern Ukrainian town of Bakhmut, which Russia seized last May after months of bloody, brutal fighting.
The gunners here are very pleased with their newly-arrived Paladins donated by western partners. The howitzers are kept hidden under tents and half-buried in the ground, due to the growing threat of enemy drones.
This winter is not going to be quiet on the front line, says Sashko, one of the crew members, as he picks up an artillery shell.
He carefully carries the 43-kg explosive round, trying not to slip on the frozen ground.
Frequent explosions in the distance are a reminder that the front line is less than 10km (six miles) away.
“This [Russian push] will last at least until the presidential elections in Russia,” says Sashko. He argues that Russia’s President Vladimir Putin needs a victory on the battlefield in Ukraine to boost his campaign at home ahead of the vote in March 2024.
While Ukraine’s soldiers are highly-motivated by the fight to liberate their own country, this is one of the most challenging times for its military since the beginning of Russia’s full-scale invasion in February 2022. And not because of the gloomy weather.
A lack of major progress in the much-hyped counteroffensive has made Ukraine’s soldiers realise that the war will drag on for much longer. They know a difficult winter is ahead of them. Troops told the BBC they need support more than ever to change the tide of the war.
“If there is no military support from the West, then things will be really bad,” Sashko says. “First Russia will seize Ukraine, then it will be the turn of Baltic states, Poland. I think Russia will not stop here.”
Ukrainian authorities recently claimed that they had received less than a third of the one million artillery shells the EU promised to provide.
Last summer, the US agreed to send controversial cluster munitions due to the shortage of those 155-mm shells. Ukraine’s President Volodymyr Zelensky also acknowledged that supplies of that type of ammunition had fallen.
A Ukrainian drone operator who directs artillery fire on the southern front line and who requested not to be named told the BBC that the number of artillery engagements from the Ukrainian side in the south had dramatically dropped over the past few months.
“During the peak period of the counter-offensive and even just a few months ago, the ratio between Russian and our artillery fire was largely 1:1 or bigger in our advantage. Now, we fire one round for every four or five rounds that Russia fires.”
The situation may become critical if Western states cut their support and the aid dries up, the soldiers say.
“Without ammunition, this will just be scrap metal,” Sashko says, pointing at the American howitzer. “It is a nice machine – we can drive it, but we won’t be able to fight with it.”
The situation on the front line has turned into what the Ukrainian military describes as a positional war, where permanent and fortified front lines make the role of artillery even more important – and the supplies of ammunition vital.
Stocks for old Soviet artillery, that use different types of rounds, are falling at an even faster rate than supplies for western artillery shells. Stockpiles of those rounds sent from allied countries are almost depleted, and production of new ones is limited, soldiers say.
“We do have [an] ammunition shortage,” admits Gorn, battery commander in the 22nd Brigade. “If we had more shells, we would have gotten far beyond Klishiivka [a village next to Bakhmut] by now. Whatever amount we get, we try to fire accurately.”
His gunners use the old Soviet 2S1 Gvozdika system, which is not known for being accurate. They improve their efficiency with the help of drones that direct fire. The crew loads the gun with Soviet 122-mm rounds after a target is identified.
But they have to wait for hours for the command to open fire – too long and too risky for the BBC crew to hang around.
A gunner with the call sign Kent explains that they wait to make sure that they’ve got a high value target. They simply cannot waste ammo on anything else.
This crew, like all others who operate aging Soviet-made howitzers and artillery systems, want to get western guns – they are faster, simpler and more accurate, they say. And their range is longer, which can be lifesaving for artillerymen.
But the fact that a $60bn aid package has stalled in the US Congress, amid a row over US border security, appears to have contributed to a sense of disillusionment among these men.
If there is no US funding, it means that their unit will be unlikely to switch to modern western guns any time soon.
The lack of aid, they say, means higher losses for Ukraine. They are angry that their lives and sacrifice might be wasted because of what they say is Europe and the US not fully comprehending the importance of military support for Ukraine.
“Our western partners must understand that if we fail to stop Russians, then they will go further,” Kent said.
“Then [Europe and America], instead of helping us, will be defending their own lands, and their own people will be dying.”