When Yuriy Shelmuk co-founded a company last year making drone signal jammers, he said there was little interest in the devices. It now produces 2,500 a month and has a six-week waiting list.

Demand shifted after the failure of a major Ukrainian counter-offensive in the summer of 2023 that was meant to put invading Russian forces on the back foot. Kyiv cited Russia's extensive use of unmanned aerial vehicles to spot and strike targets, as well as vast numbers of landmines and troops.

"Concentrated, cheap aerial drones stopped all our assaults," Shelmuk said. "There was an understanding that a new game changer had appeared."

The vast majority of more than 800 companies in Ukraine's burgeoning defence production sector were founded after Russia's 2022 full-scale invasion that enters its 1,000th day on Tuesday.

Many were set up in response to rapidly evolving battlefield conditions, including drones - first in the skies and then also on land and at sea - as well as anti-drone technology and, increasingly, artificial intelligence.

"The Ukrainian military-industrial sector is the fastest innovating sector in the entire world right now," said Halyna Yanchenko, a Ukrainian lawmaker who has advocated for local arms manufacturers in parliament.

Both Ukraine and Russia are on track to make around 1.5 million drones this year, mostly small "first-person view" vehicles that cost a few hundred dollars apiece and can be piloted remotely to identify and attack enemy targets.

In February, Ukrainian troops were already telling Reuters that the preponderance of Russian drones made it harder for them to move around freely and build fortifications.

By summer, as Russia began taking Ukrainian territory at the fastest rate since the early days of the conflict, most battered military pickup trucks sported electronic warfare (EW) domes that would have only been put on high-value equipment last year.

Shelmuk's company, Unwave, is one of some 30 firms manufacturing such systems, which block signals and use various means to disrupt computer systems inside drones.

Most anti-drone EW systems jam one, or at best a small handful of radio frequencies, meaning Russian drone pilots can sidestep jamming by hopping on to a new frequency.

EW makers thus monitor Russian drone-related online chats to understand which frequencies their drones will use.

War of robots

As losses mount and exhaustion sets in, both sides in the war are trying to replace humans with machines. Ukraine has struggled to replenish units depleted over time by fighting; Russia has reportedly turned to North Korea.

Seven officials and industry figures told Reuters automation would be the main focus of battlefield innovation in the coming year.

"The number of infantrymen deployed in trenches has decreased significantly, and combat command is possible to do online from a remote point, which reduces the risk of personnel being killed," said Ostap Flyunt, an officer in the 67th mechanised brigade.

Ukraine now has more than 160 companies building unmanned ground vehicles, according to state-backed defence accelerator Brave1. They can be used to deliver supplies, evacuate wounded or carry remotely operated machine guns.

An army colonel, callsign Hephaestus, recently left the military to start building automated machine gun systems. He said six of his products were already substituting human gunners on the front, allowing them to operate the weapons on a screen far away from danger.

Flyunt said this was increasingly common: "Modern war is a confrontation of technologies for detection, jamming, and destruction at a distance, leaving to the operator only the ability to make decisions about strikes," he said.

Arms minister Herman Smetanin also said remote warfare, including using artificial intelligence, was on the increase.

"In the near future, this will be the main direction of development, the war of robots," he told Reuters. "It's about people's lives, we need to protect them."

Ukraine hopes an innovative defence sector will provide a new foundation for an economy devastated by the invasion.

The country has poured $1.5 billion into upgrading defence manufacturing which had stagnated since Soviet times, arms minister Smetanin said, although it still relies on Western allies for shells, missiles and air defences.

Defence production capacity has grown from $1 billion in 2022 to $20 billion in 2024, but Ukraine can only afford to buy about half of that, the minister said, leaving the extra manufacturing capacity unused.

Some manufacturers complain of strict limits on profit margins and a lack of long-term state procurement contracts - an issue President Volodymyr Zelenskiy has said he intends to address.

Four companies Reuters spoke to also said they struggled to find enough qualified staff.

Kateryna Mykhalko, director of Tech Force in UA, an association of private defence manufacturers, said 85% of 38 firms surveyed by her organisation were either considering relocating operations abroad or had already done so.

The thorniest issue for many is a wartime ban on arms exports that companies want repealed in order to generate capital for expansion. Officials are concerned about public disapproval of an aid-dependent country at war exporting arms.