U.S. Army Europe and Africa soldiers together with allied forces engage in command and control drills at USAREUR-AF headquarters in Wiesbaden, Germany. During the twin exercises, dubbed Avenger Triad and Steadfast Duel, a new concept known as the Eastern Flank Deterrence Line was tested. (Christopher Osburn/U.S. Army)

STUTTGART, Germany — The first to fight on the ground in a Russian attack on NATO territory could be allied robots rather than infantrymen.

At U.S. Army Europe and Africa headquarters in Wiesbaden, top commanders have been testing out a new combat concept in which a network of early-alert sensors connects through an artificial intelligence-informed cloud system to initiate battle.

“It implies that you want to take people out of the battlefield area as much as you can, and that’s what we’re sort of really learning about,” Lt. Gen. Jez Bennett, NATO Land Command deputy commander, said Wednesday. “Hence the idea of a sort of autonomous robotic force that takes that initial punch in the event that NATO is invaded.”

During two war games this week, U.S. and NATO commanders tested out the approach, which was first unveiled by U.S. Army Europe and Africa’s Gen. Christopher Donahue in July at a meeting of Army officials in Wiesbaden.

Known as the Eastern Flank Deterrence Line, the concept is aimed at bringing ground combat techniques into the 21st century, commanders say.

In overlapping drills called Steadfast Duel and Avenger Triad, USAREUR-AF and NATO’s LANDCOM merged into one headquarters to test the defense line approach and see how ground forces would respond in the event of an attack.

Commanders said the drills marked a rare instance in which all 32 NATO member countries were gathered for an Article 5 defense scenario, referring to the alliance’s policy that an attack on one member is an attack on all.

Steadfast Duel is NATO’s largest computer-assisted command post exercise and is designed to enhance the alliance’s ability to carry out operations across a broad spectrum.

NATO senior leaders discuss operational planning during exercise Steadfast Duel in Wiesbaden, Germany, Oct. 27, 2025. (Samuel Kim/U.S. Army)

The drill incorporated USAREUR-AF staff and leaders from seven NATO corps to simulate the command of more than 100,000 NATO troops in the field.

Much of the wargaming centered on enabling fast decision-making by commanders and the need to process large amounts of live data into digestible bits so that allied forces can stay ahead of the enemy.

Avenger Triad focused on similar command and control issues. The drills drew heavily from lessons of the Russia-Ukraine war, commanders said.

At times, the war in Ukraine has harkened to earlier conflicts, with trench warfare and massive casualty numbers on both sides. Allies want to avoid sending their own soldiers into the gauntlet in the manner Russia has deployed many of its forces.

The NATO approach “is not anymore like the Second World War, with the Russians just pushing cannon fodder into the front,” said Spanish Brig. Gen. Zacarias Hernandez Calvo, LANDCOM deputy chief of staff of plans. “This is not the way we want to fight.”

Instead, the Eastern Flank Deterrence Line envisions that in a future fight, NATO will blunt any Russian offensive with an unmanned zone of operations.

“It really does learn the lessons from Ukraine, about a battlefield without people on it,” Bennett said.

In the unmanned zone, a robotic force would be put into action, keeping NATO’s human force in reserve to avoid the “level of concentrated Russian attacks that we have seen in Ukraine,” Bennett said.

The setup would preserve human combat power for counterattack and the “ability to think and act quickly to hold Russia’s own capabilities at risk in the event that it invades,” he added.

The defense line concept is already operational, but more work is needed to build it out, commanders said. For example, robotic forces are still some way off in terms of the ability to field them at scale, Bennett said.

While the defense line system is now tailored to defending NATO’s eastern front, the approach could be extended across Europe and beyond, military commanders say.

“With this successful command-and-control system established in Europe, it must be rapidly scaled and connected globally, ready to meet any threat,” Donahue wrote in a July essay that alluded to the defense line concept.

Hernandez said command and control drills such as Steadfast Duel, which concluded Thursday, capitalize on a new streamlined approach encapsulated by the defense line concept.

“This is the way all the armies in NATO are going for the future,” he said.