DONETSK REGION, Ukraine — So many drones patrol the skies over Ukraine’s front lines - hunting for any signs of movement - that Ukrainian and Russian troops have little ability to move on the battlefield without being spotted, and blown up.

Instead, on missions, they rush from one foxhole to another, hoping the pilots manning the enemy drones overhead are not skilled enough to find them inside. Expert drone operators, their abilities honed on the front, can stalk just a single foot soldier to their death, diving after them into hideouts and trenches.

The surge in small drones in Ukraine has turned the area beyond either side of the zero line - normally known as “the gray zone” - into “the death zone,” said Oleksandr Nastenko, commander of Code 9.2, a drone unit in Ukraine’s 92nd brigade. Those who dare to move day or night under the prying eyes of enemy drones “are dead immediately,” he said.

Cheap drones deployed in Ukraine have transformed modern warfare - and initially gave Ukrainian troops an advantage on a battlefield where they are perpetually outnumbered and outgunned. “This is the evolution of our survival,” Nastenko said.

But the Russians quickly caught on and began mass producing their own drones.

What followed was an overabundance of disposable, deadly drones and electronic warfare devices known as jammers that disrupt their flights. Most common are first-person-view, or FPV drones, typically controlled by a pilot wearing a headset and holding a remote controller.

“What we’re witnessing right now is blitzkrieg drone warfare,” said Andrew Coté, chief of staff at BRINC Drones, a Seattle-based drone company sending equipment to Ukraine. Coté said that drones in Ukraine are as game changing as tanks were in World War I. “It is pretty stalemate,” he said, “because if you are out in the open, you will be hunted.”

The technological advances probably have saved lives because drone pilots can work slightly farther from the zero - or contact - line than traditional infantry. But the saturation of drones, many with thermal cameras that work at night, has also shrunk the space where troops can move safely without being spotted - leading to high casualties and, in recent months, largely preventing either side from making major breakthroughs.

These conditions - combined with widespread minefields and shortages of ammunition and soldiers - now make it virtually impossible for Ukraine to retake swaths of territory as it did in 2022.

Russia, which has ample missile stocks and superior aviation power, capitalized on Ukraine’s ammunition shortages to seize the strategic eastern town of Avdiivka, and is now pushing to take more land. On Saturday, Ukraine’s commander in chief Oleksandr Syrsky warned that the situation on the eastern front had “significantly deteriorated.”

Ukraine will rely largely on drones to make it difficult for the Russians to press forward without putting expensive Russian fighting vehicles at risk whenever they move.

With large-scale drone production underway in Russia, Ukraine is racing to manufacture more than a million drones this year in hopes that it will prevent further Russian gains.

That task is turning even more urgent as Kyiv rapidly runs out of artillery and air defense ammunition from its Western partners, including the United States. For months, Republicans in Congress have blocked a $60 billion aid package proposed by President Biden.

Mykhailo Fedorov, Ukraine’s minister of digital transformation who is overseeing much of the country’s drone development, said Ukrainian drones have proved more accurate than artillery on some enemy targets. Still, artillery is a top need.

Earlier in Russia’s invasion, Ukrainian troops relied on artillery to destroy high-value targets such as Russian tanks and halt the Russian advance. Now, a severe shortage of 155-mm shells means that even if surveillance drones identify dozens of targets, few will be attacked.

“If we don’t get enough ammunition we will lose this war,” said Denys, 31, a drone commander in Ukraine’s 45th brigade who conducts surveillance deep inside Russian-controlled territory, and who is being identified only by his first name for security reasons.

In the meantime, “we are holding off their advance with FPV drones,” said Nepal, 32, a drone operator in the same brigade who, like others in this article, spoke on the condition he be identified only by his call sign, in keeping with military rules.

Ukraine has trained tens of thousands of soldiers like Nepal as drone pilots - a role that effectively did not exist when Russia invaded Crimea in 2014. In February, Ukrainian President Volodymyr Zelensky formalized the role of drone operators, establishing a new military branch called the Unmanned Systems Forces. “Repelling ground assaults is primarily the task of drones,” Zelensky said, acknowledging that the role of infantry soldiers has changed dramatically.

Ukrainian factories are producing a wide range of drone models, including ones that strike inside of Russia, and civilian volunteers are building FPVs themselves, following directions on YouTube.

Demand for drones is outpacing supply, Fedorov said. “Even if we meet all the needs that are formally there now … tomorrow there will be 10 more attack drone companies that also need drones,” he said.

The sheer number of drones means the battlefield is “almost transparent on both sides,” Nepal said, speaking from a makeshift base near the front line filled with parts for FPVs.

The devices, while fairly cheap to construct, are so strategically valuable that Nepal spends hours at his desk working to repair those seized from the Russians or fixing their own in hopes they can be used again.

Jamming systems, which disrupt drone frequencies and turn pilots’ screens to static, have made missions even more difficult. Sometimes, Nepal said, he must hit his targets “being almost blind.”

There is little besides jamming the signal that troops can do to protect themselves from a drone. Nepal often watches as Russian troops, holding assault rifles, try to save their lives by shooting down his explosive-laden drones before they crash into them.

Nepal’s commander, Fox, 32, said nonstop flights of Russian drones mean “everything is in danger.” Last fall, his troops could fly their drones freely, taking out Russian targets. Now, due to jamming, they often cannot move them much more than one mile before their screens go gray.

Stanislav, 35, who runs a drone unit in eastern Ukraine said that within a 10-kilometer radius controlled by his brigade and two others, there might be 100 reconnaissance and attack drones flying back-and-forth.

“The most challenging thing to figure out is if it’s Ukrainian or Russian drones,” Stanislav said. “When you see 10 drones in the sky there’s no way to understand if it’s our drone coming back after reconnaissance in Russian-controlled territory or if it’s their drone which is coming for reconnaissance or attacking Ukrainian-controlled territory.”

Although the jamming systems he uses, developed by Ukrainian company Kvertus, help disrupt Russian flights, they also hamper his own. He said he wishes there was a “magic button” to disrupt all signals, but with drones using an increasingly wide range of frequencies such technology is not available.

Russia knows how valuable drone pilots are to Ukraine and “are targeting our drone operators with aerial guided bombs and grad systems,” Fox said.

Nastenko compared the precision of an advanced pilot to that of a jeweler; Fox likened the skill set to that of a Formula 1 racecar driver.

On a recent mission, Nastenko’s team - working from a foxhole near the zero line - launched a Vampire drone toward Russian positions. The thermal camera combed over dead trees until it found Russian troops hiding on their side of the line. Then, the drone dropped its payload, igniting a massive explosion. A recording showed Russian troops’ bodies as they went flying.

The drone returned back to its base, where the Ukrainian troops loaded it up again and sent it back to kill any survivors. Meanwhile, another drone called a Mavic lingered overhead, monitoring Russian movements. Its camera picked up two disoriented soldiers running side by side in circles, their camouflage uniforms turned an eerie white under the thermal lens. Then they separated, looking for anywhere to hide. The Vampire drone homed in and fired again.

Intercepted communications showed that the attack, which took roughly an hour, killed eight Russian troops, Nastenko said.

Days later, troops in his unit embarked on another mission. While in the field, they came under an artillery attack, losing two of their own.

David L. Stern in Kyiv contributed to this report.

previous coverage

• US warns that China is providing Russia with drone, missile components