Iran has been developing and expanding its Unmanned Aerial Vehicles1 fleets ever since the 1980s. They now comprise a wide spectrum of types that range in size and function from aircraft size, high-flying reconnaissance UAVs to small, low-cost “suicide” drones. Until fairly recently, Israel’s military regarded the threat from Iran’s UAVs—either operated by Iran’s armed forces or by their proxies in the region—as a minor component of the overall military threat, compared to the major, strategic threats of Iran’s fleet of ballistic missiles and its proxies’ rockets deployed in Iraq, Syria, Lebanon, Yemen, and Gaza.

This view seems to have changed dramatically, judging by recent reports in the Israeli and U.S. media and strong statements made by Israel’s leadership. Amos Harel, military analyst for Haaretz, reported that “Iran relies on UAVs as a counterweight to Israel’s air superiority,” adding that “Israel’s military high command is worried by the spread of Iran’s UAV capabilities to more and more of Iran’s proxies.”2

Three months later, the same concern was expressed by top Israeli leaders. In his Sept. 12, 2021 speech to the Reichman University’s Institute for Counter-Terrorism, Israeli Defense Minister Benny Gantz disclosed that “one of Iran’s most potent weapons is its fleet of UAVs.” According to Gantz, “This is an array of lethal and precise weapons that, like ballistic missiles, can traverse thousands of kilometers. The Iranians produce and provide these air vehicles to their proxies, who in turn use them in coordination with and under the command of the Revolutionary Guard and its Quds Brigades.”3

Gantz, in fact, thereby elevated Iran’s UAVs to the top rank of threats, on par with that posed by Tehran’s nuclear program.

Israeli Prime Minister Naftali Bennett was even blunter. In his Sept. 27, 2021 speech to the U.N. General Assembly, he emphatically stated that “Iran has recently established a new terror weapon unit…. swarms of armed UAVs carrying lethal weapons that can strike anywhere, anytime.” Moreover, he warned that “Iran has already used these lethal UAVs, dubbed ‘Shahed 136,’ to attack Saudi Arabia, U.S. bases in Iraq and cargo ships on the open seas.” He warned that “Iran intends to arm its proxies in Yemen, Iraq, Syria and Lebanon with hundreds—and later with thousands—of this kind of UAV.”4

Remarkably, Bennett made no mention of the Iranian missile threat.

Taken together, Bennet’s and Gantz’s statements testify to the mounting concern in Israel over the threat of Iran’s UAVs, a threat that while not new has now attained a kind of “critical mass,” rendering it equivalent to the nuclear threat and overshadowing the missile and rocket threats from Iran and its proxies.

Apparently, Iran’s UAVs have evolved into an issue of concern for the U.S. administration, too. A recent Wall Street Journal article, titled “Iran Armed Drone Prowess Reshapes Security in the Middle East,” discloses that “Teheran uses off the shelf materials to manufacture armed drones that challenge the U.S. and its allies in the region.” The article proceeds to quote unnamed sources in Europe, the United States, and Israel who say that Iran’s fast-expanding capabilities in the design, manufacture and deployment of UAVs “Are altering the balance of power in the region.”5

Following the Oct. 10, 2021 attack by Iranian-made UAVs on U.S. troops in the Al Tanf base in Syria, the administration sanctioned Iranian persons and industries engaged in UAV design and manufacturing. It seems, then, that the United States and Israel share similar views about this new threat.

An image taken from what the Israeli military says was a Hezbollah drone downed after crossing the border from Lebanon. In the image, the drone’s operators can be seen engaging in what the IDF says is a training exercise. Source: IDF Spokesperson’s Unit.

Threat evolution

Iran’s engagement in developing, deploying and transferring UAVs to its proxies is not a new phenomenon. Iranian UAVs operated by Hezbollah penetrated Israeli airspace 16 years ago, even before the 2006 Lebanon War.

In July 2006, while that war was still raging, Hezbollah launched three or four bomb-laden UAVs towards central Israel. One suffered a technical failure and crashed near the Lebanese border, while two more were shot down by air-to-air missiles fired from Israeli F-16 fighter jets. The fate of the fourth—if there was a fourth—is not known. Following the 2006 war, Hezbollah’s Iranian-supplied UAVs made several attempts to reconnoiter Israel, all being intercepted and shot down. In addition, Iran itself tried to send its own UAVs into Israel’s airspace at least twice, once in February 2018 from an Iranian-operated airbase in Syria and again in May 2021 from Iraq. On both occasions, the UAVs were destroyed before penetrating Israeli airspace.

Dual-use goods confiscated by Israel at the Erez Border Crossing into the Gaza Strip. Among them were military and electronic equipment such as skimmers, knives, scuba gear, drones, satellite communications equipment, binoculars and more. Source: Office of the Coordinator of Government Activities in the Territories.

Since nearly a decade ago, Iran’s proxies in Gaza have been stocking up with locally made—but Iranian designed—armed UAVs. As early as 2012, during “Operation Pillar of Defense,” the Israel Defense Forces destroyed a Hamas UAV poised to take off from the old Gaza airport runway. During the July-August 2014 escalation “Operation Protective Edge,” Hamas launched several UAVs into Israel, which managed to cross the Gaza border. Two or three of them were shot down by Patriot air defense systems.

In the recent May 2021 escalation “Operation Guardian of the Walls,” Hamas unveiled a new type of UAV—unseen before in Gaza, but familiar from Iran’s proxies operations in Yemen and Lebanon. Hamas launched five or six of these “suicide drones” towards Israeli border towns. Most, if not all, were shot down by the Iron Dome short-range air and missile defense system. Hamas claimed that one managed to break through Israel’s defenses, hitting a “chemical plant” within Israel. A video clip released by Hamas shows a UAV diving and exploding near the Nirlat paint factory in Kibbutz Nir Oz, about 3 km (1.9 miles) from the Gaza perimeter.

The proficiency of Iran’s UAVs and their operators have been demonstrated repeatedly in the region ever since the onset of the war in Yemen in 2014. Iran’s UAVs operate in the skies of Saudi Arabia, the Persian Gulf, Iraq and Syria. They have been extensively used in a broad spectrum of operations, including retaliation against Islamic State (ISIS) bases, battlefield support of the Assad regime forces in their campaign to regain control in Syria, in attacking cities, national infrastructure and oil targets in Saudi Arabia, and in targeted killings of high-ranking officers and officials of the internationally recognized Yemeni government.

One of the Saudi Aramco oil processing facilities hit in a Sept. 14, 2019 combined missile-and-drone attack attributed to Iran. Source: Screenshot.

Scant attention was paid to the role of Iranian-originated, Quds-brigade-smuggled UAVs in the fighting in Yemen and the war of attrition against Saudi Arabia. However, this changed abruptly after the surprise attack by Iran’s UAVs on Sept. 14, 2019, against two of Aramco’s main oil facilities in Saudi Arabia. In a meticulously planned operation that surprised most if not all intelligence services in the West (Including Israel’s Mossad), fewer than 30 low-cost Iranian UAVs caused tremendous damage to two of Saudi Arabia’s key oil installations, reducing oil export capacity by more than half for several months.

This brilliantly conceived operation, a veritable “mini Pearl Harbor,” used mainly the “Shahed 136” suicide UAVs later mentioned by the Israeli premier’s U.N. speech. The Iranian UAV swarms reached their targets in the depth of Saudi Arabia’s hinterland with complete surprise, remaining undetected by Saudi Air defenses. Hence, no attempt was made to intercept them. Their precision was exceptional.6

In July 2021, Iran’s UAVs made headlines once again when, for the first time ever, a suicide UAV managed to hit and cause casualties aboard a commercial ship underway at sea. The oil tanker MT Mercer Street sailed from Dar-es-Salaam, Tanzania, to the UAE oil terminal of Fujairah when it was attacked on July 28 and then again on July 29 by unmarked UAVs. While the first attack or attacks failed, the second was successful. A diving UAV achieved a bull’s eye on the ship’s bridge, killing the British captain and his Romanian bodyguard.

The stricken ship was escorted by warships of the U.S. Navy Fifth Fleet and continued on its voyage to Fujairah. Upon arrival, the U.S. Central Command (CENTCOM) conducted a thorough investigation and released some of its results to the public. One of the key findings was that the debris from the attacking UAV was identical to that left by the “Shahed 136” UAVs that had devastated the Saudi oil installation in Abqaiq two years earlier. This proved the Iranian connection to the attack on a civilian ship on the high seas. As a result, Israel, the United States, the United Kingdom and Romania named Iran the perpetrator of this outrage. The international media defined it as an act of terror.

The “Mercer Street” oil tanker, managed by an Israeli owned-company, was struck by what U.S. explosives experts say was an Iranian drone in the Arabian Sea on July 29, 2021. Photo by Johan Victor/MarineTraffic.

The Japanese-owned, Liberian-flagged MT Mercer Street is operated by “Zodiac Maritime,” a London-based company owned by Israeli tycoon Eyal Ofer. The Israeli connection brought forth a theory that the Iranian action against this ship was part of a broader covert war between the two countries. One source in the Iranian media claimed that the attack was in retaliation for unspecified Israeli attacks on Iranian installations in Syria. Iran’s government, however, washed its hands of the whole affair. As in the case of the attack on the Saudi oil installations in 2019, there was no smoking gun, since the UAVs’ launch point remained unknown.

At the time of the attack, Mercer Street was sailing close to the Omani coastline, about 480 km (298 miles) away from the nearest Iranian coast. Its distance from Iran’s Omidiyeh Air Force Base, from which the September 2019 UAV attack on Saudi oil installations originated, was about 1,500 km (932 miles)—about twice as far as the distance traveled by the Iranian UAVs during the September 2019 oil attack.

One Western source hypothesized that the attack on the Mercer Street originated in Houthi-held Yemen, but this is highly doubtful. The distance between Houthi-held territory and the point where Mercer Street was struck is about 1,700 km (1,056 miles). It would be more reasonable to the Houthis to strike at the ship when it was closest to the Yemeni coast in its voyage from Dar-el-Salam to Fujairah, which is about 1,300 km (808 miles) from Sana’a, rather than attacking it when it was almost beyond reach, nearing the Strait of Hormuz. It is therefore more reasonable to assume that the attack originated in Iran.

In November, Israeli Defense Minister Gantz identified the location of two Iranian UAV bases, at Chabahar and the island of Qeshm, that he said were being used for sea control. The Chabahar and Qeshm Island bases are located 410 km (255 miles) and 670 km (416 miles) respectively from the site of the Mercer Street attack. If indeed these were the launch points for the attack, it would allow for the same “Shahed 136” that had been used against the Saudi oil installation to have been used against the Mercer Street. Nevertheless, Israeli media sources reported that the range of the “Shahed 136” had indeed been doubled, to 1,500 km (932 miles). With such a range capability, the “Shahed 136” could attack Israel directly from Iran—which is about 1200 km (746 miles) from Israel at its closest point. Perhaps this is what was on Gantz’s mind when he warned about lethal Iranian UAVs “that could traverse thousands of kilometers.”

While the number of UAVs that attacked the Mercer Street—two or three—was much smaller than the swarms that assaulted the Saudi oil installations two years earlier, the later operation was almost as impressive technically and operationally. The ability to intercept a moving ship at sea is far from a trivial achievement. This required some feats of navigation and the ability to home on a moving target, either via onboard sensors or by remote target painting from air or sea. In contrast to the attack on the Saudi oil installations, the Mercer Street attack took place in broad daylight. It stands to reason that a daylight operation was mandatory to correctly identify the target ship. This in turn could indicate that the Iranian operators maintained real-time data and visual links with the attacking UAV, hundreds of kilometers from the launch point—a capability hitherto the domain of the more industrialized countries.

The Israeli-owned cargo vessel “MV Helios Ray” in a still shot taken from video ostensibly filmed by an Iranian drone. Source: YouTube.

The Mercer Street was not the first Israeli-linked ship to be attacked in that region. On Feb. 26, 2021, the MV Helios Ray, an Israeli-owned car transporter, was attacked in the Gulf of Oman while sailing from Dubai to Fujairah. The damage forced the ship to return to the port of origin for repairs. Less than one month later, on March 25, 2021, the MT Lorry, an Israeli-owned container ship, was attacked in the Arab Sea while sailing to Gujarat harbor in India. There were no casualties, the damage was light and the ship continued its voyage. Three weeks later, on April 3, 2021, the MT Hyperion Ray, another Israeli-owned car transporter, was attacked while sailing in the Gulf of Oman towards Fujairah. In this case, too, there were no casualties and the damage was light.

Thus, the July attack on Mercer Street was the fourth consecutive attack on vessels associated with Israel. The first attack, on the Helios Ray, was carried out by attaching small explosive charges to the ship’s side above the waterline—a method used by Iran’s navy to attack oil shipping several years ago. The later attacks, however, were different. Initial reports of the second and third attacks cited “missile attacks,” but later it was reported that at least one of them was executed by a UAV. It seems that the Mercer Street incident was the third Iranian UAV attack on Israeli-linked shipping in the seas near Iran, and the first one that succeeded, albeit on the second attempt.

It can be assumed that the Iranian planners intended to cause enough damage to draw media attention and force the attacked ships to seek shelter for repairs, but not to cause the death of uninvolved civilians. On this assumption, the casualties aboard the Mercer Street were undesirable collateral damage.

Major features of the UAV threat

Apart from the above-described land and sea operations, Iran’s UAVs are busy almost daily in attacking Saudi targets in the southern and central region of the kingdom. They are also active against U.S. forces in Iraq and Syria (nine attacks and counting at the time of writing) and in sporadic incursions into Israeli airspace. The improving performance of Iran’s UAVs, as well as the burgeoning expertise of their Iranian controllers, is turning them into a significant strategic threat to Israel. This threat is fast becoming no less severe than that posed by the rockets and missiles of Iran and its proxies.

In his September address to the United Nations, Israel’s Prime Minister Bennett cited the attacks on Israeli shipping as a confirmation of the decisiveness of the new UAV threat, and was quite explicit about its nature: Swarms of hundreds, if not thousands, of Iranian UAVs, supplied to its proxies in Yemen, Iraq, Syria and Lebanon, could be used for attacking Israel. To evaluate the significance of this threat we need to assess the growing importance of UAVs in Iran’s military force structure—but to do this, we first need to define just what a UAV is.

Israeli Prime Minister Naftali Bennett addresses the United Nations General Assembly in New York on Sept. 27, 2021. Photo by Avi Ohayon/GPO.

Like manned aircraft, UAVs come in an almost infinite variety of forms and serve a myriad of purposes. Strictly speaking, any object that can fly stably over any distance—even a short one—without a human pilot on board is a UAV. This includes balsa wood, rubber-band-powered model aircraft, quadcopters purchased in toy shops and giant, remotely piloted aircraft like the U.S. Global Hawk that can fly non-stop from the United States to the Middle East (one example of which was shot down by an Iranian air defense missile in June 2019 over the Strait of Hormuz).

The term “UAV” has become even more ambiguous with the appearance of the so-called “cruise missile,” which is essentially nothing but a UAV powered by a jet engine. Iran, for example, has at least two types of jet-driven UAVs, which are designated by the media (as well as by some analysts) as “cruise missiles.”

Here, we will apply the “UAV” designation to all militarily significant unmanned aircraft, whether propeller or jet-driven.

As in Israel and the United States, Iran’s early-generation UAVs were designed for use as reconnaissance aircraft to obtain real-time battlefield intelligence. They carried video cameras and transmitted back still photos and video footage about enemy positions, deployment and movements. Later, they had air-to-ground weapons fitted under their wings, enabling them to strike targets identified through their optical sensors. Once the art of navigation by satellites was perfected and with GPS and GLONASS satellite navigation systems coming online, the Iranian turned some of their simpler and cheaper reconnaissance UAVs into “suicide UAVs,” that destroy targets by crashing into them rather than by launching air to ground munitions at them.

The IDF’s Skylark Unit prepares one of its drones for flight. Credit: IDF.

Suicide UAVs are favored by the Iranians since they can be manufactured in the improvised workshops of their proxies all over the Middle East, including Hamas and Palestinian Islamic Jihad in the Gaza Strip. The Wall Street Journal article already cited reveals that the Iranians purchase off-the-shelf commercial-grade components and materials for the production of UAVs both by themselves and by their proxies. Piston engines, for example, are purchased from China’s Ali Baba for $500 per piece, free of any export license since this small air motor has wide civilian use, including for powering model aircraft built by enthusiasts in the United States and Europe. The servo motors used to move the control surfaces of their UAVs originate in the South Korean toy industry. One of the critical components of the “Shahed 136” of Saudi oil installation fame was made in Sweden and is used in the food industry. Software for guidance and control—created by Western enthusiasts—can be freely downloaded from ArduPilot, a site that offers such software for remotely controlled air and ground vehicles.7

The manufacturing of such rudimentary yet effective suicide UAVs is simpler than the production of precision rockets—hence the growing use of UAVs in regional wars. In Yemen, the Houthi insurgents initially used unguided rockets to harass Saudi Arabia’s southern cities, but later shifted to suicide UAVs since the Saudi ground-based defense systems have more difficulty intercepting them—but perhaps also because such UAVs are easier to mass-produce in the workshops of Houthiland. Following the six-week Nagorno-Karabakh war in 2020, where Azeri attack and suicide UAVs devastated the Armenian armed forces, Iran held a giant arms exposition where it showed off and flew UAVs of all three varieties: reconnaissance, ground attack and suicide. As the unnamed Iranian official said to the Wall Street Journal: “Developing a nuclear weapon would take years. With drones, just a few months. Drones have changed the balance of power in the Middle East.”

The main drawback of combat UAVs—whether releasing air to ground weapons or crashing into the target—is the relatively small weight of explosives they can carry. Heavy Iranian rockets like the “Zelzal” or its precision sibling the “Fateh 110” carry warheads containing more than half a ton of explosives. The “Shahed 136s” that hit the Saudi oil installation and the Mercer Street carried about 20 kg (44 lbs) of explosives. At the same time, all suicide UAVs are precision weapons. The cumulative damage of a large number of small, precise warheads can be decisive, as shown in the case of the Saudi oil installation.

Iranian Fateh-110 missiles and launchers in a maneuver held in July 2012. Credit: Hosein Velayati via Wikimedia Commons.

UAVs have an advantage over rockets and ballistic missiles because of the unpredictability of their flight path. A rocket or ballistic missile travels along a direct line between the launch point and the target. Hence, since the prospective launch zone of Hezbollah rockets from Lebanon and Hamas rockets from Gaza are well known, Israel’s defense system can deploy accordingly. By contrast, UAVs can follow any route selected by their operators, and with sufficient fuel in their tanks can approach their targets via roundabout routes. For example, a Hamas UAV taking off from Gaza could theoretically approach Tel Aviv from the north. Hence, detection of and defense against UAVs must be circumferential—360º—rather than focusing on one specific direction. The 360-degree exposure dilutes the defense’s assets.

Moreover, most UAVs are small, and many are made from low-signature composite materials, and thus present reduced radar signatures. Their small piston engines have tiny heat signatures, hard to detect by thermal sensors. Flying low and slow, they prove hard to detect by radars tuned to provide early warning against fast, high flying manned aircraft—as may have happened in the recent Nagorno-Karabakh war.

UAVs are not launched in salvos but rather individually. When arriving separately at the target area, they can be picked off one by one. To overcome this vulnerability, operators developed “swarming” techniques, with multiple UAVs flying in a coordinated manner. Such swarms can, for example, synchronize their arrival at a target area—each arriving from its own unique direction—saturating the defenses both temporally and directionally. This technique was employed by the Iranians in the Sept. 2019 attack on the Saudi oil installations, where all the attacking UAVs were probably synchronized to arrive at their target within a narrow time window. The Iranians demonstrated this capability in a recent military exercise (“Great Prophet 15”) in January 2021, which featured a swarm of four “Shahed 136s” simultaneously diving and crashing into various ground targets with remarkable precision.

Thus, as Prime Minister Bennett noted, the most ominous aspect of the UAV threat to Israel is the possibility of mass raids with synchronized swarms of hundreds, if not thousands, of UAVs.

Tipping the balance of power in the Middle East?

The success of Iran’s UAVs in Saudi Arabia, and of the Azeri ones in the Nagorno-Karabakh war, shows that Israel must assume that in any war situation, Iran’s proxies in Syria, Lebanon and Gaza will deploy armed and suicide UAVs that could precisely strike key targets in Israel, such as military reserve storage depots and force concentrations. Moreover, the UAVs of Iran’s proxies will have the capability to hit armor and supply vehicles in motion, thereby disrupting maneuvering forces. Above all, they are likely to target Israel ground-based air defenses as their first priority. The accumulated damage to Israel’s warfighting capability from swarms of hundreds of precise UAVs might equal if not surpass that from salvos of rockets and missiles.

Israeli Prime Minister Benjamin Netanyahu displays a fragment of an Iranian drone destroyed over Israeli airspace in February 2018 during his speech at the Munich Security Conference. Credit: GPO.

The strategic significance of the growing UAV threat seems to be the subject of debate within Israel’s defense establishment. According to an unnamed military source quoted in Harel’s Haaretz article, the Iranian UAVs “are not game-changers. UAVs can harass, gather intelligence and deter, but cannot achieve victory.”  The Armenians, soundly defeated by Azerbaijan’s fleets of ultra-modern UAVs, would have agreed with that unnamed Israeli officer’s assessment.

Decades ago, the IDF made the same mistake of underestimating the significance of an earlier threat, when it determined that “missiles and rockets don’t win wars” and tried to block the development of anti-missile defenses.

It seems that the political leadership of the country does not share the optimistic assessment of the quoted Israeli officer, expressing their concerns in high-level international forums. In fact, Prime Minister Bennet dedicated as much time to the UAV threat as to the Iranian nuclear threat in his recent U.N. speech—indicating that he does not see Iran’s UAVs as secondary weapons of “harassment, intelligence gathering, and deterrence” but as a viable strategic threat.

It may well be that the IDF has in the meantime rethought its position, as indicated by recent media reports. An article on the international air exercise held on October 2021 in Israel stated that “Israel’s Air Force is closely tracking two issues of concern: the deployment of Iranian ground-based air defenses in Syria, and their enhanced use of UAVs.”8

A recent article in an Israeli daily disclosed that Israel has been acting in the past few months to mobilize the international community to combat the spread of Iran’s UAVs, assigning it equal weight to Iran’s nuclearization in the struggle against Iran’s quest for hegemony in the Middle East.9 Judging by these reports it seems that the top Israeli leadership does perceive Iran’s UAVs as a veritable game-changer.

The challenge of UAV defense

Roughly speaking, combat UAVs come in two classes: The first includes medium to large UAVs flying at medium altitudes, used for reconnaissance and for attacking ground targets with precisely guided air-to-ground missiles or glide bombs. UAVs of this class operate individually rather than in swarms and are designed to return to base after completing their missions—in other words, they are multi-use systems designed for repeated operations. The challenge of defending against them is rather similar to that of defending against manned aircraft, except that UAVs generally fly at lower speeds.

The second class includes single-use suicide or “kamikaze” UAVs. Generally speaking, they tend to be smaller and less sophisticated than Class 1 UAVs. They fly at low to very low, ground-hugging altitudes, and can operate in swarms. From the point of view of the defender, they pose a threat more akin to that of a precision rocket salvo.

Iranian Quds force sites targeted by Israel in Aqrabeh, Syria, on Aug. 24, 2019, to thwart an imminent drone attack. Source: IDF Twitter.

The UAVs launched against Israel to date by Hezbollah, Hamas and the Iranians themselves were mainly (but not exclusively) of the first class and were intercepted and shot down by Israel’s air force. Initially, hostile UAVs were shot down by air-to-air missiles fired from fighter aircraft. On one occasion, an Iranian UAV arriving from Syria was shot down by gunfire from an Apache helicopter. Later, during the 2014 “Operation Protective Edge” and the 2021 “Operation Guardian of the Walls,” Hamas UAVs were shot down by ground-based air and missile defenses—Patriot and Iron Dome respectively.

UAVs of both classes are not immune to air defenses, whether ground-based or airborne. If anything, the opposite is true: It is relatively easy to shoot down a slow-flying UAV, provided that it is detected in time and provided that the defender uses the appropriate weapons against small and stealthy targets. The challenge is timely detection and tracking and, in the case of UAV swarms, avoiding being overwhelmed. Moreover, UAVs are precision weapons, hence it is not enough to kill some or even many of them: The operational requirement is to kill them all—in the language of missile defense, to achieve a zero or near zero leakage rate. Defending against swarms of UAVs arriving simultaneously from every direction at treetop level is a formidable challenge to any air defense system, a challenge that may well require the development and fielding of new technologies and operational doctrines.

UAV use in the region

“UAV wars” in which air defenses were pitted against ground-attack UAVs have occurred in northwest Syria, in Libya, in the South Caucasus, in Saudi Arabia, in Yemen and most recently in Ethiopia. In the Second Nagorno-Karabakh War of October–November 2020, Azerbaijan threw into the battle its newly purchased fleet of ultra-modern class 1 and class 2 UAVs, practically obliterating the Armenians’ Soviet-era ground-based air defense systems. Losing the capacity to defend their airspace paved the way to a crushing Armenian defeat.

In the still-ongoing civil war in Libya, Turkish class 1 UAVs deployed in support of the internationally recognized government in Tripoli demolished the ground-based air defenses of the rival government of Benghazi, and proceeded to wreak havoc on the Benghazi ground forces, thereby allowing the Tripoli government to break the siege on its capital city and regain control of large tracts of the country.

During the seven-day long “Operation Spring Shield” in February-March 2020, Turkish Class 1 UAVs demolished the opposing Syrian air defenses, then proceeded to destroy Syrian tanks, troop concentrations, and command posts.10

Recent reports from the ongoing civil war in Ethiopia are painting a similar picture. The Ethiopian government, on the verge of defeat by the Tigray rebels, has recently turned the table with the aid of class 1 UAVs of Chinese, Turkish and Iranian origin.

The situation in Saudi Arabia is more complex. Since 2015, the Houthis in northern Yemen have been conducting a war of attrition against the kingdom, using rockets, ballistic missiles and UAVs–mainly class 2—to harass population centers, military installations, economic value targets and state symbols across the length and breadth of Saudi Arabia. In the south, close to the Yemeni border, the targets are mainly towns, airports and oil facilities. In the kingdom’s deeper hinterland, the Houthis target state symbols (e.g., royal palaces) and oil industry infrastructure, such as pumping stations serving oil pipelines.

The Iranians surreptitiously intervene in this harassment campaign, by launching “Houthi looking” UAVs from their territory into Saudi Arabia. The Saudis’ extensive air defenses are vigorously battling the incoming UAVs using ground-based defenses (Patriot) and airborne defenses combining early warning aircraft with manned interceptor fighter aircraft. The information offered by the media on the evolution of the air campaign in Saudi Arabia is at best sketchy, providing an incoherent picture of the situation due to the heavy use both sides make of verbal and photographic data for propaganda purposes. All the same, some general conclusions can be gleaned even from the incomplete and biased information published to date.

One conclusion is that Saudi Arabia is encountering some difficulties in defending its hinterland against class 2 UAVs, especially when they arrive from unexpected directions. The most outstanding example was the failure to detect and engage the class 2 UAVs coming from Iran’s direction that struck the oil installations in September 2019. This, however, was not the only case. In February 2021, for example, three suicide UAVs launched from Iraqi territory struck a royal palace in Riyadh, the capital city.11 It seems that in both cases Saudi Arabia air defenses failed to detect the incoming UAVs and were powerless to intercept them.

In the southwestern regions of the kingdom, its air defenses are enjoying some success against Houthi UAVs (according to Saudi and U.S. sources, an outstanding success). From photographic evidence released by the Saudi military, it seems that they use ground-based Patriot batteries in concert with Saab 2000 early warning aircraft and F-15 fighter jets armed with air to air missiles. The Saudis sometimes claim the destruction of dozens of Houthi UAVs in a single day, and release convincing-looking video footage. Nevertheless, there is no doubt that some UAVs manage to penetrate the defensive shield.

A smoke trail of a Patriot missile intercepted a drone approaching Israel from Syria in the northern Israeli city of Tzfat on July 11, 2018. Photo by David Cohen/Flash90.

For example, the Abha International Airport, about 150 km (93 miles) away from the closest Yemeni border, sustained casualties and damage from Houthi UAVs during the summer and fall months of 2021 (the Saudis claim that the UAVs were intercepted and that the casualties and damages were inflicted by the falling debris). This highlights the defensive requirement of an extremely high success rate against the incoming UAVs; the damage from the “leaks” overshadows the damage prevented due to those UAVs that were destroyed.12

Saudi Arabia, whose huge territory is almost the size of Western Europe, lacks a nationwide early warning system against low and slow UAVs. This leaves its borders practically open to incursion by low- or medium-altitude aircraft. Its ground-based air defenses, consisting mainly of the older generation Patriot 2 and the newer Patriot 3, are optimized for intercepting high flying combat aircraft and ballistic missiles rather than low flying UAVs. The prospects of the kingdom buying Iron Dome systems (initially optimized against rockets, and only recently upgraded for UAV interception) are practically nil, but it may yet emulate the Emirates by purchasing the newly developed South Korean M-SAM II, a joint development with Russia’s defense industry.

Acquiring and fielding those systems, however, could take years. Saudi Arabia’s nascent military industry announced in 2020 that it is developing an anti-UAV system. Still, from the published details it seems that the new system will offer only localized defense against quadcopters (“drones”) rather than horizontal flight UAVs of both categories.13 It seems that Saudi Arabia has no immediate military option to seal its skies against the incursion of hostile UAVs from Yemen, Iran, or Iraq. Perhaps this is what compelled the kingdom to seek a diplomatic solution and to open negotiations with Iran. It is perhaps not too far-fetched to conclude that the simple, unsophisticated UAVs originating in Iran managed to humble the powerful Royal Saudi Air Force, gaining for Iran a significant strategic achievement. The statement of the unnamed Iranian official quoted above that the UAVs are tipping the military balance in the Middle East may thus not have been far off the mark.

Meanwhile, in another corner of the Middle East, UAVs have been battling Russian air defenses in Syria. When Russia acquiesced to Bashar Assad’s entreaties to save his regime against the then-victorious insurgents, Assad granted Moscow an airbase in Khmeimim and a naval base in Tartus, both in the northwestern corner of Syria. As soon as the Russian intervention commenced, those two bases—but mostly the airbase—came under frequent insurgent attack, initially from mortars and later from UAVs.

On Dec. 31, 2017, the Khmeimim airbase suffered a major insurgent strike, initially thought to come from mortars but later confirmed as coming from UAVs. The attack caused the death of two Russians and damaged several aircraft. Unofficial sources claimed that eight aircraft were hit, two of which were total losses. One week later, on the night between Jan. 5 and Jan. 6, 2018, 13 insurgent UAVs attacked both Russian bases (10 UAVs attacked Khmeimim and three attacked Tartus). It seems that this time the Russians were ready.

According to their statements, the attack was completely foiled, with seven UAVs being downed by ground-based air defenses and the rest forced to land by a Russian cyber operation. The photographic evidence released by the Russians shows two types of UAVs: One is a Chinese-made, hand-launched UAV sold openly through Ali Baba under the name “Skywalker.” The other was a rather largish and rudimentary radio-controlled balsa-wood model aircraft of unknown provenance, carrying tiny bombs under its wings and probably built by the insurgents themselves. The UAV attacks on the Russian bases are still going on sporadically. For example, in July 2021 the Russian reported downing 13 hostile UAVs, and a month later, in August, they reported the downing of a formidable number—45 in all. Russia claims a 100% success rate and no losses or damage in the ongoing battle against the insurgents’ UAVs.

The Russian military is largely silent about its doctrine and methods for combating UAVs, but non-Russian sources report that three major components are involved: First, the Russians re-tuned their radars to detect the small, low and slow vehicles. Second, they set up systems to interfere with satellite communication (GPS and perhaps Russia’s own GLONASS), and third, they use Electronic Warfare (EW) to disrupt communication between the UAVs and their operators. It is also possible that the Russians are using cyber warfare to hijack incoming UAVs and land them safely.

The ground-based air defenses of the Russian enclaves are based largely on the SA-22 Pantsir, which is equipped with two 30mm rapid-firing anti-aircraft guns—a legacy of WWII— and 12 small, short-range, heat-seeking ground-to-air missiles. While Pantsirs operated by Syrian and Libyan forces have been overwhelmed by modern Turkish UAVs, it seems that in the case of the Russian bases in Syria, the Pantsir remains effective against the rudimentary UAVs launched from the last anti- Assad enclave in North-Western Syria.

Comparing the UAV defense of Saudi Arabia and the arguably more effective Russian defense, four parameters stand out: the size of the defended area, the suitability of the defensive weapons to the mission of killing UAVs, the role of electronic and cyber warfare, and the sophistication of the aggressor’s air vehicles and operators. Territorial size seems to be decisive:  The immense territory of Saudi Arabia and its extremely long borders make it difficult to erect a hermetic early warning fence against low flyers, allowing practically free ingress of UAVs into its territory. In contrast, the two Russian bases in Syria are the size of small towns, facilitating impermeable early warning fences around them.

As for weapons, Saudi Arabia relies on heavy manned fighter aircraft and Patriot air defense systems, both designed to engage high-flying manned aircraft rather than low, slow and cheap UAVs.  Using expensive Patriot interceptor missiles against fiberglass, propeller-driven mass-produced model aircraft is tantamount to using a sledgehammer to kill gnats: Feasible but highly inefficient. The Russians, by contrast, are using lower-tech, ground-based air defenses, combining anti-aircraft guns with what are essentially shoulder-launched anti-aircraft missiles. The Russians are using electronic countermeasures (ECM) to disrupt the hostile UAVs and perhaps also cyber warfare (CW) to force them down. There is no information on the similar use of ECM or CW by the Saudis.

Finally, the aggressor’s level of sophistication seems to also play a part. The Iranians have demonstrated high skill in inserting swarms of UAVs into Saudi Arabia’s hinterland, circumventing defensive systems, remaining unseen by early warning systems, and avoiding ground obstacles. The Syrian insurgents in the Idlib enclave that keep attacking the Russians with their simple UAVs lack the Iranian sophistication—so it stands to reason that their UAVs fly in straight lines along the shortest route—and hence the most predictable route—from the Idlib enclave to the Russian bases.

Elements of effective defenses against Iran’s UAVs.

Today, the burgeoning UAV threat is an issue of concern not only in Israel but to the West at large. Western defense industries are proposing a welter of new anti-UAV weapons, some realistic and some bordering on science fiction. Of the cutting-edge weapons being developed, the closest to maturity is the high-power solid-state laser, on which significant progress has recently been achieved both in Israel and abroad. A development program for a 300 kW mobile laser system has recently been initiated in the United States. Since the level of power of the laser beam is directly proportional to its kill rate, it may well be that such powerful lasers will be able to deal even with synchronized UAV swarms.

The Elbit Systems 100-kilowatt laser system will be able to shoot down large hostile UAVs, smaller drones, rockets, missiles and particularly long-range threats as they travel through the air, according to the company. Credit: Israeli Defense Ministry.

Another cutting-edge technology being experimented with is microwave beams, which “fry” the electronics of incoming UAVs. One U.S. company came up with the idea of reusable kinetic interceptors that kill target UAV by metal-to-metal collision, without any explosives. The spent interceptor is then parachuted down for recycling. Other companies propose interceptor UAVs that shoot air-to-air missiles at the incoming hostiles or physically crash into them.

Class 1 UAVs that are generally used for reconnaissance and ground attack tend to be relatively large and heavy, necessitating suitable runways. Repeatedly damaging such runways by offensive actions could slow down class 1 UAV operations. In contrast, the smaller types of class 2 UAVs are launched from zero-length rails or catapults and are accelerated to take-off speed by small rockets or pressurized air bottles. Zero-length catapults of the types unveiled by Hamas during the May 2021 “Operation Guardian of the Walls” can be assembled in a few minutes before the launch and disassembled immediately after it. Hence, they present temporary, quickly vanishing targets. Accordingly, the chances to hit them while deployed are slim, to say the least. As a result, the response to most class 2 UAVs—i.e., the smaller types of suicide UAVs—will probably be defensive rather than offensive. In the case of Israel, the defensive brunt will befall on the shoulders of Israel’s Air Defense Command.

Unlike Saudi Arabia, Israel’s small territory facilitates the establishment of a seamless early warning perimeter around all its borders. Detection of low, slow and small UAVs is the cornerstone of effective defense, without which no viable defense is feasible, as we see in Saudi Arabia. Israel’s air defenses had already made significant steps in this direction when it upgraded the Iron Dome radars to detect small, low flying UAVs, proving its effectiveness during the 11-day “Operation Guardian of the Walls.”

The Drone Dome system mounted on a truck. A deomnstration held by Rafael in February 2020 saw laser inteceptions of multiple drones in the desert achieve 100 percent success rate. Credit: Rafael Defense.

The UAV threat does not replace the rocket and missile threat, but rather adds to it. Adding the mission of UAV defense to the already existing mission of rocket and missile defense could overwhelm the defense systems. It is therefore necessary to take quantitative measures to beef up the defensive shield. The number of defensive systems capable of dealing with both kinds of threats must be increased. Even then, synchronized UAV swarms coming from every direction could locally overwhelm the defense. Hence, the addition of new cutting-edge kill systems should be investigated, such as laser (already in development in Israel) and microwave systems. ECM systems might be able to destroy UAVs in masses. hence their integration in the defensive array should be pushed forward. Israel’s army has already employed ECM, during “Operation Guardian of the Walls,” but it seems they were of the local, short-range “drone dome” type made by Rafael, basically optimized against short-range quadcopters. Disrupting horizontal-flying UAVs at long distances will probably require more powerful ECM systems, such as the Israel Aerospace Industry Elta Division “Scorpius” recently unveiled by the Israeli Ministry of Defense.

Finally, and most importantly: The cost per kill must be driven down. In combating rockets and missiles, the cost of defense has always been and remains higher than the cost of offense, giving the aggressor a financial advantage. This disparity becomes even more pronounced in the case of UAVs. As the aggressor descends the technological ladder– i.e. switching from relatively expensive guided missiles and rockets into toy-like, fiberglass aircraft powered and guided by amateur-grade systems, the defender is forced to climb the technological ladder, from interceptor missiles to lasers and microwaves.14 Ultimately, it will be battlefield economics, as expressed by the cost per kill, that will determine who has the upper hand: aggressor or defender.

A long-exposure picture showing Israel’s Iron Dome anti-missile system firing interceptors at rockets fired from the Gaza Strip, as seen from Ashdod, May 15, 2021. Photo by Avi Roccah/Flash90.

Conclusion

Iran’s UAVs can no longer be seen as secondary weapon systems used to “harass, gather intelligence and deter.” Rather, they have grown into a major weapon system that, when applied properly, can be a game-changer by themselves, as potent as the Islamic Republic’s new generation of precision rockets and missiles. The concerns voiced by Israel’s premier and defense minister with regard to these weapons are both justified and timely. It can only be hoped that Israel’s defense establishment learns from the experience of others and rapidly deploys the required offensive and defensive means to prevent Iran’s UAVs from tipping the military balance in the region.

Uzi Rubin was founder and first director (1991-1999) of the Israel Missile Defense Organization in the Israeli Defense Ministry, which developed, produced and deployed the country’s first national defense shield—the Arrow Weapon System. He subsequently served as Senior Director for Proliferation and Technology in the National Security Council (1999-2001), and directed several defense programs at the Israel Aerospace Industries and in the Defense Ministry. He was twice awarded the Israel Defense Prize (1996 and 2003), and was also awarded the U.S. Missile Defense Agency “David Israel” Prize (2000). He has been a visiting scholar at the Stanford Center for International Security and Arms Control, where he directed a study on missile proliferation.

This article was first published by the Jerusalem Institute for Strategy and Security.

Notes

1. While the term “drone” is widely used to denote all unmanned vehicles that rely on an aerodynamic lift for flying, it is also used to denote small rotary-wing flyers that are sold for entertainment and used by the general public. To avoid ambiguity, this paper will use the technically correct term “Unmanned Air Vehicles (UAVs)” to denote all types of unmanned flyers, whether fixed or rotary-wing.

2. Harel, A., “Iran’s UAVs are a partial response to Israel’s air superiority,” Haaretz, July 16, 2021 (Hebrew)  https://www.haaretz.co.il/news/politics/.premium.HIGHLIGHT-1.10004417

3. Zeitun, Y. and Fuchs, G., “Gantz exposes Iran’s training of terrorists’ operators of UAVs,” Ynet, Sept. 9, 2021 (Hebrew) https://www.ynet.co.il/news/article/hyqqqfjgf.

4.  For Bennet’s speech, see, https://www.youtube.com/watch?v=FuTvx6QFWUo

5. Fouson. B. and Nissenbaum, D, “Iran Armed Drone Prowess Reshapes Security in the Middle East,” Wall Street Journal, Oct. 7, 2021, https://www.wsj.com/articles/irans-armed-drone-prowess-reshapes-security-in-middle-east-11633530266

6. For a more detailed description and analysis of the September 2019 attack on Saudi Arabia oil installations, see Uzi Rubin, “Saudi Arabia’s Black September” https://jiss.org.il/he/rubin-saudi-arabias-black-september/

7. https://ardupilot.org/

8. Zaitun, Y., “Eurofighters and F 35s against Russian air defenses: report from the international air exercise in Israel,” Ynet, Oct. 25, 2021 (Hebrew) https://www.ynet.co.il/news/article/ryugnr7iy

9. Lis, Y., “Before the sanctions, Israel provided the US with information on the Iranian UAVs,” Haaretz, Oct. 30, 2021 (Hebrew) https://www.haaretz.co.il/news/politics/.premium-1.10339681

10. For a more detailed description and analysis of the UAV wars in Libya and Northern Syria, see Uzi Rubin, “UAVs in the skies of the Mediterranean.” https://jiss.org.il/en/rubin-uavs-in-the-skies-of-the-mediterranean/

11. Payman, T., “Explosive-laden drones that targeted Saudi Arabia’s royal palace in the kingdom’s capital last month were launched by Iran-backed militia from inside Iraq,” Mail Online, Feb. 25, 2021 https://www.dailymail.co.uk/news/article-9300063/Drones-targeted-Saudi-royal-palace-launched-Iran-backed-militia-inside-Iraq.html

12. This lesson was already learned from the V1 “Flying Bombs” campaign against Britain during WWII. The British, forewarned of the imminent attack by their excellent intelligence services, prepared a multi-layer defensive shield consisting of belts of anti-aircraft guns, integrated with squadrons of fighter aircraft (including the first British jet fighters). In time, the defensive shield proved its capability and achieved a nearly 90% success rate. Yet the few UAVs that did break through killed hundreds and caused extensive damage in London, forcing the allies to divert offensive resources from the land battles in France to ground and air assaults on the V1 launching sites.

13. Helu, A., Saudi Arabia is developing a new counter-drone system, Defense News, Jan. 1, 2020. https://www.defensenews.com/unmanned/2020/01/08/saudi-arabia-is-developing-a-new-counter-drone-system

14. The similarity to the Improvised Explosive Devices (IED) comes to mind. IEDs—primitive mines consisting of lumps of explosives wrapped in rugs that are left in the open on roadsides have been taxing the best brains in the defense industries on how to detect and destroy them in time. High power lasers have been proposed for this task.

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