Small Drones Are Helping Israel Navigate the Urban Battlefield in Gaza

It isn’t just tunnels. In the dense urban battlefield of Gaza, the Israeli military has been flying these quadcopters—essentially small helicopters with four rotors—into buildings before sending in soldiers. The devices are also providing smaller units with aerial reconnaissance and being used as guided munitions.

The small drones are just one new piece of Israel’s unmanned aerial arsenal, which military officials say has played an essential role in minimizing their casualties as they rapidly advance through a densely populated, well-fortified and extensively booby-trapped battlefield.

Israel also operates a large fleet of fixed-wing unmanned aircraft, some as large as F-16s and others small enough to be carried on a soldier’s back, that carry out a mix of surveillance, reconnaissance and airstrikes—an ability it admitted it had for the first time last year. The largest aircraft can fly up to altitudes of 45,000 feet and stay airborne for nearly a day and a half, while the smallest flies at 5,000 feet and can stay aloft for a few hours.

Israeli military officials say those drones are still a critical backbone of support for the military. But it turns out that small, cheap quadcopter drones are in many ways more useful on some parts of the battlefield—like in tunnels.

About a decade ago, Israel’s National Security Council had deliberated whether quadcopter drones would have an impact on the battlefield and concluded they wouldn’t, said Jacob Nagel, a former Israeli national security adviser.

Now he said, “The air in Gaza is full of them."

The increasing adoption of small, commercial drones is evident in conflicts around the world. Both Russia and Ukraine have relied heavily on quadcopters for surveillance and attacks, while Hamas used small drones as part of its Oct. 7 assault. Since then, thousands of commercial drones have made their way into the hands of Israeli soldiers on the battlefield and civilians looking to defend themselves.

The quadcopter has become a lifeline for Israel’s smaller, less-equipped units, such as those made up of reservists called into battle after the Hamas attacks.

The drones, however, weren’t expected to be used to explore tunnels. Israel originally used heavy robots connected to the surface through a cable to search the hundreds of miles of passages that Hamas has dug beneath Gaza. But the tunnel floors are often filled with trash, tripping up the robots, while some passageways proved to be too narrow for them to be operated.

Israel also tried using robotic dogs, but they are expensive and heavy.

The small drones can create 3-D maps of the tunnels, are completely untethered and can fit through small spaces. They can also create their own communications networks underground, with each small drone flying as far as it can before becoming a new relay node that will allow the next drone to fly further.

It wasn’t just Israel that failed to originally foresee how important quadcopters would become in war zones. The U.S. military had for years focused on building larger, more expensive drones before realizing only too late that it had ceded the small drone market to China.

Today, China’s SZ DJI Technology is the world’s largest maker of consumer drones, and its inexpensive quadcopters have become popular on the battlefield.

At the outset of the war in Gaza, when there was a rush to get small drones into the hands of Israelis, many of those sent were Chinese-made DJI drones, said employees at private drone companies working with the Israeli military.

In one video released by the Israeli military, soldiers could be seen lowering a DJI Mavic 3 drone into a tunnel below a hospital compound in Gaza City.

Israel soon cracked down on the use of DJI’s drones inside Gaza, said the employees at the private drone companies. The operators of the Chinese-made drones, which aren’t designed for the battlefield, can be located using off-the-shelf hardware that Hamas could likely acquire.

A senior Israeli military official said an effort had been made to standardize what kind of drones soldiers could use on the battlefield.

“One of the [Israel Defense Force’s] top acquisition priorities right now is indoor drones for use in hostage rescue operations in the Hamas tunnels and subterranean environments," said Blake Resnick, CEO of the U.S. drone company BRINC.

Resnick said he was in Israel earlier in December and the Israeli military purchased some of the company’s LEMUR 2 drones, which are designed for search and rescue operations. The drones are being used primarily for hostage-rescue operations in the Hamas tunnels and subterranean environments, according to Resnick.

The Israeli military declined to comment on what type of drones it is using inside Gaza.

Aviv Shapira, the Israeli co-founder and CEO of drone company XTEND, first began working with Israel’s military several years ago to use quadcopters to take down incendiary balloons that Gazans, some at the behest of Hamas or other militant groups, were sending into nearby Israeli farms to start large fires.

Now, he said, the Israeli military is using the company’s drones for a variety of purposes inside Gaza. Some go into the tunnels. Some can break through windows and explore inside buildings. Others are equipped with robotic arms carrying a small payload, such as a small adhesive explosive that can blow a door open, fly in and drop grenades.

He said the military’s Yahalom, or diamond in Hebrew, which specializes in finding and destroying Hamas’s tunnels, uses the drones to drop things onto mines or booby traps usually found around the tunnel exits.

XTEND’s small Xtender drones, which can carry about 5 ounces, are equipped with cameras that can create real-time 3-D mapping, helping them fly indoors and underground in tunnels. The drones can work underground by operating as radio relays, helping the operator reach the furthest drone.

These functions, initially designed for indoor use, have now become essential for outdoor use in Gaza, said Shapira, because both Hamas and Israel are jamming Global Positioning Systems for navigation and radio signals for communications.

Multiple drones—sometimes called a swarm—can also be directed by one operator. Using a virtual-reality headset with picture-in-picture feeds, the operator can use one drone to break into a building through a window or a door, and land a second one at the entrance for additional surveillance. Meanwhile, a third can search the building for the target.

“We found that three is the magic number," said Shapira.

Heather Somerville contributed to this article.

Write to Dov Lieber at dov.lieber@wsj.com