MILAN — In the early hours of Dec. 26, five North Korean drones entered South Korean airspace, with one traveling as far as the capital Seoul.

Although authorities claimed the UAVs did not fly near critical security facilities, the systems did operate above the country’s territory for several hours.

Defense forces failed to counter the threat, even after deploying fighter jets, attack helicopters and firing warning shots. The helicopters fired a combined 100 rounds, according to the Defense Ministry.

One fighter jet scrambled that day, a KA-1 light attack plane, crashed during takeoff; its two pilots safely ejected, defense officials said.

One drone returned to the North after three hours in South Korea, while the rest disappeared from South Korean military radars one after another, the Joint Chiefs of Staff said.

Following the incident, South Korea sent surveillance assets near and across the border to photograph key military facilities in the North, the Joint Chiefs said, without elaborating further.

Incidents like the one in late December present a national security threat to the South, as the drones flew long enough to potentially collect intelligence and take images. More alarming, however, is the fact that “South Korea has suffered similar drone incursions repeatedly — in 2014 and 2017, for example — and each time the military says it will improve its counter-drone systems,” according to David Hambling, a writer of drone warfare and technology topics.

North Korea is reportedly expanding its drone capabilities, with a United Nations report from 2016 estimating the country possessed about 300 drones of various types.

It’s unlikely the South’s military was unaware of those drone development efforts, but the “sophistication of the systems as well as their ability to swarm and evade detection” did come as a surprise, said Ken Gause, a North Korea expert with the U.S.-based Center for Naval Analyses think tank.

This suggests “North Korea has benefitted from outside technology, potentially from Russia or Iran,” Gause told Defense News.

Hambling also noted that Russia’s use of Iranian-made drones against Ukraine “is likely to encourage North Korea to increase efforts in this direction, posing an asymmetric threat which Seoul seems poorly prepared for.”

Failed countermeasures

Some experts agreed that South Korea’s failure to shoot down the drones in December simply comes down to the fact that unmanned aircraft are complex and difficult to counter — something that is especially true for smaller and faster UAVs.

“To begin with, air defenses are naturally designed to deal with threats from aircraft, cruise missiles and helicopters, which are all relatively large and fast,” Hambling said. “Many were previously designed to specifically filter out small, slow, low-flying objects, as there were almost invariably birds which would otherwise create many false alerts.”

Case in point: The morning after the Dec. 26 incident, South Korea preemptively deployed fighter planes to its border in response to what turned out to be a flock of birds.

As drones are typically smaller and generally contain fewer metallic elements than larger aircraft, they are “naturally stealthier with a smaller radar signature than larger aircraft, making them harder to detect,” Hambling explained.

Lt. Gen. Kang Shin Chul, South Korea’s chief director of operations at the Joint Chiefs of Staff, acknowledged in a televised statement following the Dec. 26 intrusion that the country lacks the ability to detect and strike small surveillance drones with wingspans less than 3 meters (9.84 feet). However, the South has radars and other assets to spot and shoot down larger combat UAVs.

“We have seen this in Saudi Arabia, Russia and Ukraine, all of which have had high-tech defenses penetrated by small, low-tech drones,” Hambling said. “South Korea is certainly not alone in suffering this kind of breach.”

Bruce Bennett, a defense researcher at the think tank Rand, said South Korea’s failed counter-drone measures are due to a lack of focus on that capability. Instead, he explained, the country has prioritized combat aircraft and naval programs.

In addition, he told Defense News, the Army has faced “limitations to its military budgets, tremendous demographic problems, and a lack of personnel from 2005 and on, which led to [a downsizing] of the military, and the trade-off was to acquire new, expensive technologies for the manpower they were losing.”

Next steps

Three days after the airspace incursion, the South Korean military staged large-scale drills to simulate shooting down drones. The exercise involved land-based anti-air guns, UAVs playing the role of enemy drones, and a total of 20 fighter jets, attack helicopters and unmanned assets.

While there was no live fire, it was the country’s first set of major counter-drone drills since 2017, according to military authorities.

And following the aerial trespassing, South Korean authorities have promised to increase defense spending, specifically allocating about $440 million for counter-drone efforts, which would include the development of an airborne laser weapon and a jamming system focused on small drones.

In 2021, the Defense Acquisition Program Administration announced a project to develop a laser anti-aircraft system to protect against mini-UAVs, with local firm Hanwha designated as the test product developer.

Hanwha Defense spokesman Jeff Sung told Defense News that the company is scheduled to complete development of this system in 2023, with initial production scheduled for 2024. Hanwha will make the second iterance of what Sung called “a truck-mounted laser anti-aircraft system” over the next couple of years.

The company is currently trying to improve the system’s mobility by developing smaller and lighter platforms as well as diversifying the output power of lasers to address different types of targets, Sung added.

South Korea is also adding a third squadron dedicated to addressing UAV threats, and the country is now accepting bids for a portable anti-drone jammer for deployment next year.

But experts say more must be done to ensure drone incursions are stopped. Bennett said South Korea must be prepared to not only jam drones but also target their GPS systems with enough electrical power to make the system fail.

North Korea has years of experience developing jamming capabilities to counter GPS-guided weapons that the South and its American allies might deploy in the event of a conflict on the Korean Peninsula. The North reportedly maintains a regiment-sized unit focused on GPS jamming near its capital, and the country previously used Russian-made equipment and satellite navigation technology to jam signals near border regions.

“The experience North Korea has built over the last 20 years in doing this likely makes its drones harder to jam,” Bennett said.

Meanwhile, Hambling recommends South Korea carry out a complete assessment of its air defense systems to identify shortcomings. This could also answer questions about the Dec. 26 incident, he added. “Were the UAVs misidentified? Or were they correctly identified, but did the rules of engagement not allow them to be tackled? Were no suitable assets available for the interception? Or were they simply not detected?”

Gause agreed, noting the importance of identifying where the drones launched from and maintaining an ongoing list of possible future launch sites.

However, he warned, “North Korea does have the ability to pop up from underground facilities to launch things like missiles and drones, which gives the U.S. and Korea very little warning.”

Hyung-Jin Kim with The Associated Press contributed to this report.

Elisabeth Gosselin-Malo is a Europe correspondent for Defense News. She covers a wide range of topics related to military procurement and international security, and specializes in reporting on the aviation sector. She is based in Milan, Italy.

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