Forterra, a US builder of autonomous vehicles, revealed today that more than 100 of its self-driving ATVs have been deployed in conflict zones in Ukraine for the past nine months, in what the company believes is the largest deployment of autonomous ground vehicles in combat by any US defense tech company.

“I believe this to be true of every defense technology that’s ever been created—until you hit the realities of combat, you’re just not going to know,” Scott Sanders, Forterra’s chief growth officer and a former US Marine officer, told TechCrunch.

Funded by US defense dollars, the mission is part of growing effort to transform the US military through its support of Ukrainian resistance to Russian invaders. While aerial drones have garnered much of the attention in the fight, the dynamics they’ve created — extensive no-go zones where surveillance can lead to death from above — have led Ukrainian strategists to seek ground-based autonomy as well.

“There’s nowhere to hide,” Sergeant Major Corey Wilkens, who leads a program developing autonomous vehicles and tactics for the US Army, explained. “You become very, very vulnerable to be able to be attacked by [first-person view drones], other sorts of drones dropping munitions, artillery, mortar, the full range of things that they have.”

Ukraine is already building its own uncrewed ground vehicles (UGVs) to help move supplies and munitions, or evacuate wounded soldiers, but they are typically battery-powered and can only carry up to 250 kilograms, according to a soldier in the Ukrainian army who has worked with the vehicles and who TechCrunch won’t identify for security reasons.

Forterra’s Lancer vehicles, based on Polaris ATVs and equipped with a custom-built sensor and compute stack, are gas-powered and can carry 750 kilograms of cargo, making them more versatile and useful. “The bottom line is that this UGV for logistics and just maintaining our defense is the most important UGV in Ukraine,” the soldier said. “It’s fucking fantastic, and we are dying to get more.”

They didn’t feel that way at first. The Ukranian Armed Forces have had have mixed experiences with Western contractors bringing new tech to the battle, and at first Forterra’s offerings felt a little too geared for the high-end requirements of the US Army. Modifying the vehicle for the situation—particularly, by adding a Starlink satellite internet antenna—made it a huge value add.

Since arriving in Ukraine last October, the vehicles have driven more than 2,500 miles across more than 1,100 missions, carrying 777,440 pounds of total weight and completing 52 casualty evacuations. Some has been lost in combat, particularly if they get stuck in deep mud or other terrain where Russian forces can target them at leisure.

Forterra has learned some useful lessons — about electronic warfare, updating their software from afar, how to maneuver in challenging conditions, and ensuring their vehicles don’t break down. The company, which has raised more than $500 million in venture funding from funds like XYZ Venture Cpaital and Moore Strategic Partners, is now better positioned to compete for lucrative national security contracts.

They’ve also seen the limits of autonomy: For now, Ukranian soldiers have mainly been teleoperating the vehicles in combat zones, in part because they’re too valuable to lose and in part because autonomous vehicles aren’t quite ready for the realities of war.

While, for example, the vehicles can navigate autonomously across diverse terrain, they’re not quite at the point where they can identify unexpected enemy forces and react appropriately. “We actually need to be able to respond to the enemy threats, live, while it’s in front of the enemy, which the autonomy doesn’t know how to do yet,” the Ukrainian soldier explained.

Forterra, which began work on autonomous vehicles 20 years ago, is working on how to combine the kinds of algorithms that gave us self-driving cars with newer generative AI software that allows machines to react to their surroundings in a generalized way. As with other autonomous systems, one of the key obstacles is gathering the right data.

“There’s a lot of things you have to do that aren’t available in an open source model because they’re not things that humans do, whether that’s figuring out how to navigate a minefield or [operating] a weapon system,” Sanders told TechCrunch. “You need to be able to turn the dials and some things more of a classical robotics approach, and then leverage AI where you need to.”

Competitors in this space are solving similar challenges, like Scout AI, which raised $100 million earlier this year to train foundation models and develop a suite of autonomous platforms for the military that includes UGVs. Other startups like Field AI and Overland AI are trialling UGVs with the US military.

Even with the limitations on UGVs, American military experts are convinced that its time to invest in these tools. “Ground autonomy is achievable now and we’ve seen it,” Wilkens said.

Scott Philips, the chief innovation officer at Forterra, visited a Ukranian unit’s operations center to see the vehicles in action first-hand, winning respect from the unit for visiting an area in range of Russian attacks.

“What struck me most was seeing exactly where the seams are: which steps are still manual, where data has to be re-entered or re-verified by hand, and where the team has already found ways to automate or speed things up,” Philips told TechCrunch. “That’s the kind of ground truth you can’t get from a slide deck because it shows you precisely where better tooling could take pressure off the people doing this work in real time.”

One challenge issued by the Ukrainians: Make it cheaper. Forterra’s Lancers aren’t expensive for their category, thanks to relying on Polaris’ commercial supply chain for the vehicle itself, but they are still too valuable to be deployed as freely as UAVs can be.

“Attrition is just a fact of this battlefield, and we have lost a few at this point, and it hurt, and we need more, and therefore we need them cheaper,” the Ukranian soldier told TechCrunch.