• Israel's potent air defenses are increasingly threatened by low-flying drones.
• Two retired Israeli generals say it needs new defenses against this "low sky" layer.
• Israel pioneered targeting air defenses with drones in a stunning victory four decades ago.

Israel's air and missile defense system is arguably the best in the world, having proven this year it can down Iranian ballistic missiles and Hamas-fired rockets. Its Iron Dome is the epitome of this success and is only one of many systems. But while these can protect Israeli cities, they have an increasingly glaring problem — they can't protect themselves from low-flying drones, two retired Israeli brigadier generals warn.

"We have to defend our air defense," wrote Eran Ortal and Ran Kochav in a blog for the Begin-Sadat Center for Strategic Defense at Bar-Ilan University near Tel Aviv, Israel.

Ortal and Kochav fear that enemy drones could knock out air defense systems such as the vaunted Iron Dome, enabling ballistic missiles, manned aircraft and artillery rockets to strike Israel without being intercepted. "The Israeli Air Force does continue to rule the skies, but under the noses of the advanced fighter jets, a new air layer has been created."

The authors call this the "low sky" layer. "The enemy has found a loophole here. The Air Force (and, within it, the air defense corps) is required to defend against the combined and coordinated threats of missiles, unmanned aircraft systems and rockets."

Over the past year, Israel's air and missile system has achieved remarkable success against a range of projectiles launched by Iran, Hamas and other Iranian proxies, including ballistic missiles, cruise missiles, artillery rockets and mortar shells. For example, Israel — with the assistance of the US, Britain and other nations — reportedly intercepted 99% of some 300 ballistic missiles, cruise missiles and large attack drones launched by Iran in April 2024.

However, Israel has struggled against small exploding drones launched by Hezbollah, the Iran-backed militia in Lebanon. More than a hundred Israeli soldiers and civilians have been killed or wounded by these UAVs, including 67 who were wounded when a drone hit a building in northern Israel in October. Still, the situation is a far cry from the Ukraine war, where hordes of small drones have rendered battlefield maneuver almost impossible.

Nonetheless, Ortal and Kochav worry that Israeli air defenses were designed in the pre-drone era, when the threat to Israel came from aircraft and ballistic missiles, a critique that also applies to Western- and Russian-made systems. "This array was built over the years under the premise of Israeli air superiority. The air defense itself was not supposed to be hunted."

"The enemy is able to penetrate deep into Israel and engage the air defense system in one lane while other aircraft take advantage of the diversion and penetrate in another, more covert lane. It can identify targets and strike immediately using armed or suicide UAS. Above all, it strives to locate, endanger, and destroy key elements of the air defense system itself."

Israel relies on a multilayer defense system, with long-range Arrow interceptors targeting ballistic missiles above the Earth's atmosphere, the medium-range David's Sling handling ballistic and cruise missiles about 10 miles high, and the short-range Iron Dome stopping cruise missiles, short-range rockets and artillery and mortar shells at low altitude. All depend on the production and reloading of missiles adequate to the threat.

The problem is that these three systems can't protect each other. "The degree of mutual assistance and protection between the layers is relatively limited," Ortal and Kochav wrote. To optimize the allocation of a limited supply of interceptor missiles, "each tier was designed to deal with a specific type of missile or rocket. Iron Dome can't really assist Arrow batteries or support their missions. This limitation is equally true among the other layers."

Nor are Israel's air defenses built for survivability, such as creating decoy missile batteries and radars to protect the real ones or frequently relocating systems. "The degree of mobility, protection and hiding ability of the Israeli air defense system is inadequate. Unlike similar systems in the world, our air defense system was not built with synchronization as a critical goal."

Their solution? The creation of a fourth layer focused on point protection of the radar, missile launchers and troops that operate them against rockets and drones that have penetrated the first three layers. Air defenses must be camouflaged and should be mobile enough to change location before the enemy can target them.

Ironically, Israel itself was one of the pioneers of using drones to suppress air defenses. Stung by heavy losses from Soviet-made surface-to-air missiles in the 1973 Yom Kippur War, Israel used drones in during the 1982 Lebanon War. By using unmanned aerial vehicles that mimicked manned aircraft, Israel lured Syrian air defense radars into coming online so they could be destroyed by anti-radiation missiles. The Israeli Air Force destroyed 29 out of 30 anti-aircraft missile batteries in the Bekaa Valley without loss and downed more than 60 Syrian aircraft.

Israel's Air Force became so dominant that the ground forces discarded their tactical anti-aircraft weapons (though the IDF recently reactivated the M61 Vulcan gatling cannon for counter-UAV defense on the northern border). Meanwhile, the IDF's air defense corps switched its focus from anti-aircraft to missile defense.

"The working assumption was, and remains to this day, that Israel's Air Force rules the skies," wrote Ortal and Kochav. "The job of air defense, therefore, is to focus on missiles and rockets. This assumption is no longer valid."

Michael Peck is a defense writer whose work has appeared in Forbes, Defense News, Foreign Policy magazine, and other publications. He holds an MA in political science from Rutgers Univ. Follow him on Twitter and LinkedIn.