Ukraine says its counteroffensive is advancing and wants to consolidate it 3:19

(CNN) -- Two Ukrainian soldiers huddle around a drone controller in the dark, their faces illuminated only by their screen.

"Oh, something is burning," says one of them. They just dropped a bomb on a Russian target.

The overnight assault is part of a coordinated Ukrainian offensive near the besieged eastern Ukrainian city of Bakhmut, which CNN had exclusive access to.

"We will attack their front line and our guys will advance on the enemy," says one of the drone pilots, who responds to his callsign "Groove."

Ukrainian ground troops are equipped with Western night vision equipment and have an advantage in night operations, but Kyiv's ground attack aircraft are not adapted to darkness, so this drone unit nicknamed "Code 9.2" is taking a step forward.

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"Drones see night as well as day," explains 'Groove'. "We see the infantry, we hit the vehicles, the cannons, everything we have to destroy."

They are using Ukrainian-made "Vampire" aerial vehicles, a hexacopter acquired by the Kyiv government, part of an initiative led by the Ministry of Digital Transformation to supply technology to Ukrainian forces on the battlefield.

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A Ukrainian soldier removes the safety from a Smerch bomb. This type of ammunition is loaded onto drones and then dropped on Russian positions. (Credit: CNN)

"Each drone is equipped with a thermal imaging camera, so it can operate effectively at night. They can carry up to 15 kilograms of payload," Ukraine's Deputy Prime Minister and Minister of Digital Transformation Mykhailo Fedorov said in a Telegram video last August, announcing that 270 of these machines would be sent to the front lines.

"The military will use them to destroy both armored cars and tanks, as well as enemy defense structures, fortifications or ammunition depots."

That's what Groove and his unit have been doing.

Videos recorded with night-vision cameras from its drones and provided to CNN show drones dropping bombs on several Russian armored vehicles, including a recent attack that destroyed a modern Russian T-90 tank, one of the newest and most advanced models Russia is deploying to Ukraine.

"Sometimes it's a lot," says Groove, as he searches the area with his drone, trying to locate Russian forces. They chase some Russian vehicles, dropping bombs at them as they go.

"At the moment we don't see many. There was a vehicle but we didn't give it," he adds.

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Ukrainian drone pilots are able to see their targets through their controllers, even at night, with the help of night vision. (Credit: CNN)

As the drone attack accelerates, other units join the battlefield: powerful artillery makes itself heard, spraying the moonlit Russian positions at high speed with cluster munitions donated by the United States.

Grad multiple launch rocket systems fill the sky with their fast, hissing shells, mortar units add up, targeting Moscow's armies with the help of flares, and infantry fighting vehicles rush to the front to assault Russian lines.

It's a full-blown assault and, at his headquarters, the commander of Code 9.2, alias "Flint," says this operation has been weeks in the making.

"We've been preparing it for more than a month," he says, as his men prepare the ammunition they will drop on Russian positions.

"It's a combined assault," he adds, explaining that the push south of Bakhmut is designed to take advantage of recent gains in the area, where Ukraine was able to regain significant territory from Russian control.

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The "Code 9.2" unit uses these Ukrainian-made "Vampire" drones to attack Russian targets even at night. (Credit: CNN)

Offensive in the south, advances in the east

Kyiv has concentrated much of the Western equipment it received in the south, where Ukrainian forces have been advancing along two axes: from Orikhiv to Melitopol and from Velyka Novosilka to Berdyansk.

German-made Leopard 2 tanks and American Bradley infantry fighting vehicles, among others, were sent to the area to support Ukrainian forces in their assault on Russian positions. The ultimate goal is to reach the Black Sea and cut off the supply route from Russia to Crimea. So far, progress has been slow and modest, with Ukraine regaining only a few small villages in the south.

Ukrainian soldiers load drones and ammunition into the back of a U.S.-donated Humvee before a night raid. (Credit: CNN)

Far less talked about have been the operations in the eastern part of the country, where Kyiv's forces have slowly but steadily retaken tens of square kilometers since Russia's brutal assault on Bakhmut last winter.

"Here we're breaking their line of defense and we're hitting them well," Groove says. He says the Russian mercenary group Wagner, responsible for much of the Russian advances during the winter, returned to the area.

"Yes, Wagner is here too," he says. "They came back, quickly changed commanders, and came back here."

Groove believes the group's presence is partly intended to make up for staff shortages on the Russian side. "[Russia] gathered troops from the surrounding areas and brought them here," he says. "They don't have much staff left here."

But this is a slow fight—a war of attrition—and with less advanced Western equipment than their compatriots on the southern front line, Ukrainian forces are forced to rely more on intelligence than physical strength.

"We change tactics constantly," explains Commander Flint. "It's like boxing. We go for the body and then switch to the head."

Russian War in Ukraine