Radar and jamming technologies are the keys to figuring out why South Korea was unable to down even a single one of the five North Korean drones that intruded into the South’s airspace December 26.
Even though one of the North’s drones got as far as northern Seoul, it appears South Korea had difficulty locating the tiny aircraft on radar and more difficulty in tracking them. In the end, the South may have lacked equipment to jam the drones’ data channels or satellite navigation.
Because South Korea could not locate the drones, it sent up fighter aircraft to try and find them and, when identified, shoot them down. Although the South fired over 100 rounds of ammunition, not one North Korean drone was hit.
Whether the South Korean pilots really saw the North Korean drones or picked them up on aircraft radar is open to doubt. The pilots might just as well have been shooting at birds rather than unmanned aerial vehicles.
Overall, the performance of South Korea’s air defense against drones was dismal.
The type of drone launched by North Korea isn’t known. Korean authorities claim that these were small drones, but whether they were fixed wing or quadcopters isn’t known.
South Korea claims it has effective solutions against larger drones, although it has not said what.
Truly effective solutions must include advanced radars. Small quadcopter drones use electric motors and the drones are typically made of plastic. Still, advanced radars can detect even those small drones.
The best modern radars optimized for drone detection have features that other radars, including commercial air-traffic control and military sensors, lack.
These radars focus on detecting low and slow drones that can sneak under the coverage of standard radar. Many anti-drone radars have built in libraries that can assess whether the threat is a drone and not a bird or other object, and can even specify its type. They can reject noise and clutter and ignore radar returns from flocks of birds.
A major drawback for drone detection radars is range. Most operate best at short range, meaning one mile or less.
Some of the better anti-drone radars combine radar with an electro-optical sensor making identification and tracking easier, and also add electronic directional interception that can jam the control signals the drone needs for its operation. One of those systems, Elta’s Drone Guard, was successful in tests at the US Army’s Yuma Proving Ground in Arizona.
The typical drone used today has a data link for operator control of the drone and for sending imagery and other data back to the control center. Radio transmission can be relayed to and from a control center or from airborne platforms, including other drones.
More expensive and sophisticated drones, especially those with long range and endurance, use satellite communications to handle command and control and data transmission such as imagery.
Global positioning systems, also used in virtually all modern drones, include the US Navstar, the Russian Glonass and the Chinese BeiDou navigation systems. Today, inexpensive radio receiver chips and small antennas can make use of all three systems at the same time, making jamming difficult.
Generally speaking, it is easier to jam or disrupt RF (radio) control and data channels than it is to jam or disrupt GPS. However, GPS jamming and spoofing are used as part of the broader effort to knock out drone threats.
One of the attractive features of Elon Musk’s Starlink is that it is very difficult to jam because of the thousands of satellites that support the system. Starlink itself is not yet functional on drones, but it almost certainly will be in the future.
Whether small or large, drones mostly rely on data channels and GPS systems. The Iranian Shahed-136 is a little different. It is a kamikaze or suicide drone, a loitering munition that is pre-programmed with target coordinates and uses GPS, but it has no command and control and data channels that could be jammed.
Drones of the next generation are expected to be increasingly autonomous and may passively receive guidance from emitters other than GPS satellites. For example, radio towers at known locations and triangulation could make it possible for a drone to avoid GPS jamming and spoofing.
We know precious little about the North Korean drones. We also do not know whether South Korea tried to jam them, or even if South Korea had the equipment to do so.
What we do know is that North Korea has learned that it can use drones to successfully penetrate South Korean airspace. North Korea has also learned that its drones could successfully send South Korea’s jet fighters on a five-hour wild goose chase.
During the fruitless South Korean Air Force effort to track down and destroy North Korea’s drones one South Korean KA-1 turboprop light attack fighter, which was being sent off to chase the North Korean drones, crashed on takeoff. Both pilots safely ejected.
In all, South Korea wasted millions of dollars and tons of fuel to no avail.
A best guess is that South Korea was unprepared and unequipped to deal with a drone threat from North Korea. South Korea’s defense agencies need to rapidly assess why the failure happened and take steps to acquire the equipment they need to prevent another intrusion in future. Apologies, already offered, are not an adequate response.
North Korea has learned that South Korea was not prepared and is vulnerable to drone strikes. This will almost certainly encourage future bad behavior.
Stephen Bryen is a senior fellow at the Center for Security Policy and the Yorktown Institute.