Ukrainian and Russian forces are racing to develop and produce unmanned aerial vehicles, which can target everything from trenches to state-of-the art equipment on the battlefield.

One of the most potent weapons in the war has been FPV drones. They have made it almost impossible for both Ukrainian and Russian troops to move on the battlefield without being spotted from above. These drones, which carry explosives, can be guided to a target kilometres away, and cost as little as $500 to produce. Russia, like Ukraine, aggressively targets soldiers’ positions and equipment with FPVs.

Doctors and staff working at medical stabilisation points in Donbas now say most of the battlefield injuries they treat are from such drones.

There are no reliable estimates of how many FPV drones Russia is able to manufacture every month. Ukraine plans to produce a million FPVs this year, but soldiers and commanders in drone units say they need to double or triple this number if they hope to keep up with Russian troops.

To more quickly supply Roman’s brigade with drones, former jewellers and mechanics sit in a village house near the frontline, soldering parts for FPVs that can immediately be deployed. Brigades also collect downed Russian drones, which are then taken apart and examined by army engineers who are desperate to keep up with the pace of development on the Russian side.

Roman’s phone rings and he picks up, switching to French. His wife is calling from Marseille to ask about Marcel the dog and the vaccinations he will need for a short leave that Roman is planning to France. The couple married just before Roman enlisted to fight, and in his final week in France he drew up a will to make sure she would be taken care of if he died at war.

Like many Ukrainians, one of his best friends from childhood was killed in the fighting two years ago. Afterward, Roman had the words “hate” and “revenge” tattooed above his knuckles, a reminder of the emotions that keep him fighting.

But drone warfare, unlike the close-quarter fighting he conducted in the forests, does not always provide the gratification he seeks. Video clips of the bomb drops, often edited by the soldiers themselves with a hip-hop soundtrack and shared on social media, have an artificial, almost unreal quality about them.

“If I see someone is dead, if we’ve killed someone, I have zero moral satisfaction, it’s just like a video game,” Roman says. Often, he wonders what will actually satisfy the anger and sadness that he feels.

“So your friend is gone. How many invaders do you have to kill to avenge him? 10? 100? 1,000? You’re not going to get your friend back,” he says.

Soldiers in Ukraine clearly delineate life before and after the war.

Even Roman, who has a background in martial arts and easily fits his new role of commander, never dreamed of becoming a soldier. A look at his social media photos from just a few years ago reveals a different man: carefree and smiling on a messenger bike, eating pizza with his friends, posing in a rice paddy in Bali.

Another soldier describes that sense of disconnect as missing the person you once were and not recognising the new person you’ve become. When there’s a lull in his work, Roman lingers on such thoughts.

“My wife is constantly asking, ‘When is it going to be over?’ And I say I don’t have a fucking answer,” he says. At first, he thought he might be away from home for a year or two. Now, he thinks the war will continue for at least a few more years.

Although he’s not interested in demobilising and leaving his men behind, Roman agrees that Ukraine needs a way to help fighters rest. Some of Ukraine’s most motivated men and women were the first to volunteer in 2022. Now, so many of them are dead, injured, or exhausted. It’s not enough just to draft more people to take their place, Roman says; they need to be properly prepared and trained.

“You can’t keep the same people constantly on the front line.”

But the decision of Ukrainians like him to continue fighting isn’t really a choice, he says. It’s a question of life or death for his people and his country. And if Russia prevails in Ukraine, he’s convinced no one in Europe will be safe.

“For Europe and the whole world, we’re on the front lines defending it,” Roman says. “Because this motherfucker will never stop just in Ukraine,” he adds, referring to Putin. “If you let him get away with it, he’s not going to stop over here.”

Sitting in the windowless basement in front of the monitors, Roman loses track of time. Outside, above the destroyed rooftops of village houses, the night sky is full of stars. In an area north of Roman’s command centre, artillery units defending Ukraine’s eastern front waited for new deliveries of ammunition to arrive.

Ukraine’s shortage of artillery shells has become a decisive factor in its struggle to repel Russian advances. Russia’s new offensive outside of Kharkiv in northeastern Ukraine is likely to put further strain along the eastern front, where artillery units have been carefully prioritising targets and rationing shells. In an April interview, Zelenskiy said that Russia was firing shells at a ratio of 10 to one to those of Ukraine.

One of Russia’s targets is Kupiansk, a northeastern city in the Kharkiv region that was captured by Russia in early 2022 and retaken by Ukrainians later that year. Today, Russian forces are about 10 kilometres away. Oleksii, a soldier in an artillery unit in the 57th Motorised Brigade, is preparing to return to his position in the city after spending a few days resting in a nearby village house.

Oleksii, 27, volunteered to fight five years ago after Russia’s 2014 annexation of Crimea. Since then, the town in the Zaporizhzhia region where he grew up has been reduced to rubble. His comrades are all motivated and want to fight, he says, but their biggest concern is the acute shortage of shells.

“When you work and when you have enough shells, you can work and you understand you are destroying the enemy,” Oleksii says. In 2022, one artillery installation could fire 40, up to 100 shells a day. Now, the number has been reduced to two or three shells a day, maybe a dozen on a busy day, he says.

In February, Zelenskiy said Ukraine had received just 30 pr cent of the one million shells the European Union promised to deliver by March. The European Commission did not respond to questions about the shell delivery.

By the time Oleksii arrives at one of the brigade’s artillery positions, a spring storm has started. Rain is falling and thunder cracks overhead. The hulking 2S1 Gvozdika, a self-propelled howitzer, sits hidden under a cluster of branches and khaki netting, while soldiers take shelter in a dugout nearby.

The unit commander, a slim man with dark hair named Yurii, boils water on a camping stove as his men wait for an order to fire on a column of Russian infantry. Stirring a cup of tea, one of the soldiers says the months-long shell shortages have made Ukrainian forces on the front lines exceedingly vulnerable. Without shells, artillery units like theirs are unable to cover for infantry on the front lines.

“If the Americans had passed the package sooner, Russians wouldn’t have gotten so close to Chasiv Yar,” says Yurii, the 53-year-old commander. “They wouldn’t have taken so many villages and we wouldn’t have to fight to take back these villages.”

Russians have factories across their country where they can produce all manner of weapons and ammunition, Yurii says, while Ukraine is largely reliant on the goodwill of Europe and the United States.

“Russians can shoot their artillery like it’s a machine gun,” the commander says. “It’s endless.”

As the wind picks up outside, the men argue over the US election in November and what Trump’s possible return would mean for the war.

“But he won’t win!” exclaims one of the soldiers.

“Even if he did, he’ll still have to help Ukraine,” another says. “When he’s president he won’t be able to ignore the opinions of his people.”

Trump campaign spokesman Steven Cheung told Reuters that the former president would make negotiating an end to the war “a top priority” in a second term, and that European nations need to pay “more of the cost of the conflict.”

‘We are battling an enemy that wants to not only take our territory but to wipe us out,’ says a soldier who goes by his call sign, “Huntsman.”

The problem, Yurii says, is that even after all of the horrors of the past two years of war, there are still so many people in Europe and the US who do not accept all that Putin and the Russian military are capable of.

The horrific images of civilians slaughtered in Bucha after its occupation, the pulverized cities of Mariupol and Bakhmut. The tens of thousands killed, the endless portraits of dead Ukrainian soldiers shared on Facebook and Instagram, the never-ending funeral processions for fathers and brothers, the videos of children draped over their coffins.

“It’s not possible, I guess, just by looking at the photos” to comprehend the horrors of this war, Yurii says. But Oleksii, the soldier in the artillery unit, says Ukrainians have little choice but to keep fighting.

“For our entire history we’ve been fighting,” he says, rubbing the dust out of his eyes.

The men fall quiet. They sit side by side on narrow military cots, taking sips from their cups. Suddenly, the radio comes alive with an order. The soldiers dash out of their dugout and prepare to fire.

• A Reuters report