Inside the northern Ukraine training center where units learn to fight Russian drones

KYIV, Ukraine -- In a secret location in Northern Ukraine sits one of the country's biggest training centers for mobile air defense units.

In the large open-air area, soldiers train to shoot drones with machine and anti-aircraft guns mounted on pick-up trucks. Some of those weapons are at least two times older than the young Ukrainian soldiers who are learning to operate them.

"Everything we have, every help we get, we use it to create mobile fire groups to fill every inch of space here," Lieutenant General Serhii Nayev, responsible for Ukraine's Northern border defense, told ABC News during a recent visit to the training center.

More than 600 miles long, the border touches both Belarus and Russia. With winter coming, here in the North, there is no fog of war, apart from half a million mines, according to Nayev. But the real threat comes from the air.

Far from towns and prying eyes, Ukrainian instructors are launching dummy drones -- a central part of the training for mobile air defense crews. It is an imitation of defending against attacks from the Russian’s Iranian-made Shahed drones -- a daily routine for Ukrainian air defense forces.

Six crews using different types of anti-aircraft guns are trying to hit a small drone, firing thousands of rounds. Yet, 5 minutes later, you can still see it maneuvering through the clouds of smoke in the sky.

"Two bullet holes," says the drill instructor after checking the drone, which landed safely.

In the real attack scenario, such an outcome would mean using modern Western air-defense systems to destroy an enemy drone as a last resort option, firing missiles which on average cost 100 times more than each Shahed-131/136 drone. But the cost of even one UAV hitting its target could be enormous, especially with winter coming.

"We understand that there is currently a resource war going on. The Russian Federation gets its resources with the help of the Axis of Evil -- it is North Korea, it is Iran," Lt. Gen. Serhii Nayev told ABC News. “And we, with the help of our partners, receiving air defense equipment from them, are opposing the Russian Federation with their resources. It must be understood that the reduction of aid will really hit our defense capabilities. But we will fight with what we have.”

According to Ukrainian Air Force and Defense Intelligence, in the last two months, Russia fired more than 800 drones to Ukraine, having kept around 870 cruise and ballistic missiles in stock for major attacks against the country's energy infrastructure. An abnormally warm autumn is possibly the only factor stopping it for now. And as much as Ukraine is trying to prepare -- training hundreds of such mobile air-defense teams -- it is no longer about the quantity in this war.

"Technology is critical. The target for which, according to the old Soviet-style technologies, it was necessary to spend 100 shells -- with the help of Western technologies, much less is needed, and it is measured in numbers up to ten, so the technology always outweighs the number. And I will emphasize once again that this help is very, very important to us," Nayev said.

Since the beginning of the full-scale invasion, Ukraine has successfully prevented Russia from occupying most of its territories, with the battles for Kharkiv and Kherson being two major victories for the Armed Forces of Ukraine.

But the last counteroffensive in the south so far brought little gains in more than five months, serving as the biggest proof the war has changed since Ukraine's early success. Russians are adapting and evolving their tactics using more advanced weapons like Lancet kamikaze drones and remote mining with MLRS rockets while heavily relying on their air superiority in the frontline and occupied areas.

Nayev warned that if Russia continues to increase weapons production and improve technologically with the help of its allies, war could again expand beyond the East and South.

"We are getting ready for that," he said. "We're building defenses, putting mines, and training our forces."