Haeil underwater drones, which North Korea claims is capable of carrying a nuclear warhead, appear at a North Korean military parade at Kim Il Sung Square in Pyongyang on the evening of July 27, 2023, to mark the 70th anniversary of what it calls Victory Day, commemorating the signing of the 1950-53 Korean War armistice.YONHAP
Jeong Yong-soo
The author is an editorial writer and the director of the Unification and Culture Research Institute of the JoongAng Ilbo.
At approximately 9:22 p.m. on March 26, 2010, the 1,270-ton patrol corvette Cheonan broke in two and sank about 2.5 kilometers (1.5 miles) southwest of Baengnyeong Island.
Three months later, a joint investigation involving South Korean civilian and military experts and specialists from the United States, Australia, Britain and Sweden concluded that an underwater explosion involving 250 kilograms (551 pounds) of high explosives had generated a powerful shock wave and bubble jet beneath the ship's port side, at a depth of six to nine meters.
The Navy recovered the propulsion unit of a North Korean CHT-02D torpedo, providing crucial evidence of a surprise attack.
North Korea's underwater warfare strategy originated in the destruction of its naval forces during the 1950-53 Korean War. Soviet-made mines became its principal means of resistance. After the armistice, UN Commander Mark Clark established the Northern Limit Line (NLL) to prevent accidental clashes near five western border islands.
Facing overwhelming naval disadvantages, Pyongyang developed asymmetric capabilities, assembling approximately 70 submarines and submersibles. During the 1970s, it imported diver propulsion vehicles from Yugoslavia for underwater infiltration and surprise attacks.
Unable to challenge combined South Korean and American naval forces conventionally, North Korea adopted a maritime guerrilla strategy exploiting enemy complacency.
Now it appears to be pursuing nuclear-powered submarines, potentially transforming its underwater capabilities.
On Oct. 15, North Korea tested Zam-2.0, a new high-speed precision-guided torpedo system, according to state media. Its specifications and actual capabilities remain unverified.
If Pyongyang's claim that it uses rocket propulsion is accurate, the weapon could be a supercavitating torpedo, which creates an air cavity around its nose to minimize underwater resistance.
Combining extreme speed with precision guidance could challenge Korean and American naval defenses. Such technology remains difficult even for advanced military powers.
North Korea previously tested its Haeil underwater drones in 2023 and 2024, claiming they could carry nuclear warheads. Pyongyang asserted that Haeil-2 traveled 1,000 kilometers underwater over 71 hours and six minutes.
The regime claims these weapons could infiltrate enemy waters and generate devastating waves against ports and warships.
Alongside Zam-2.0, North Korea has deployed two 5,000-ton destroyers this year, expanding its modernization efforts beyond land-based weapons.
Some dismiss these developments as exaggerated claims about unreliable technology. But treating repeated weapons demonstrations as mere bluffing risks dangerous complacency.
How North Korea finances and develops advanced weapons despite its economic difficulties deserves scrutiny.
Even while pursuing dialogue with Seoul and Washington, Pyongyang has consistently invested in military capabilities, declaring that peace rests upon its weapons.
Its relatively inexpensive development system may rely on reverse engineering, cyberattacks and the theft of defense technologies through state organizations, including the Reconnaissance General Bureau.
More troubling is the possibility that these underwater weapons and modern destroyers represent a strategic shift toward sea denial, restricting Korean and American naval operations.
This could fundamentally alter security conditions in the Yellow Sea.
North Korea has recently accelerated construction of barriers along the land border. Strengthening its navy could accompany efforts to turn waters around the NLL into another military flashpoint.
In 1999, Pyongyang unilaterally announced its own maritime boundary. The following year, it demanded that South Korean vessels use only two designated routes to reach the five border islands.
These measures effectively pushed the NLL considerably southward.
North Korea then lacked sufficient naval strength to enforce its claims. Today, however, its expanding nuclear and conventional naval capabilities could support attempts to invalidate the NLL and extend its maritime jurisdiction.
Its declaration of two hostile Korean states, incorporated into party rules and constitutional provisions, further raises concerns about territorial ambitions.
Following the Cheonan sinking, a senior Joint Chiefs of Staff official acknowledged that authorities had detected a North Korean submarine leaving its base but had not anticipated an incursion into Korean waters.
The shallow Yellow Sea had encouraged assumptions that submarine operations were unlikely. That failure illustrated the dangers of underestimating an adversary.
North Korea insists that impossibility has no place in its vocabulary and that determination can enable an egg to pierce rock.
Such rhetoric may encourage reckless military ambitions, but confronting them requires imagination and creativity.
Rather than assessing individual North Korean movements in isolation, Seoul must understand the broader strategic picture.
Inter-Korean relations can shift abruptly between confrontation and engagement. Preparing for unexpected military developments is therefore essential.
This article was originally written in Korean and translated by a bilingual reporter with the help of generative AI tools. It was then edited by a native English-speaking editor. All AI-assisted translations are reviewed and refined by our newsroom.
