Won Gon Park, the Chair of the EAI North Korea Studies Center, predicts Kim Jong Un's potential invasion strategies for South Korea based on the site visits he made during the ROK-US Ulji Freedom Shield exercises in March. Park explores the likelihood of North Korea launching a nuclear attack, noting the envisioned scenario of an armed conflict starting at the Northern Limit Line and quickly escalating to a limited war involving low-yield nuclear weapons. Despite this, Park argues that Kim is unlikely to opt for such a self-destructive strategy that would almost certainly result in heavy losses. Nevertheless, he notes that North Korea continues to leverage its nuclear capabilities as a deterrent, aiming to prevent the U.S. and South Korea from initiating conventional warfare against it.

TRANSCRIPT (Subtitles)

Let’s take a look at whether the DPRK can attack the ROK with its nuclear weapons. Kim Jong-un’s recent actions suggest DPRK’s “strategic decision to go to war.” On the 76th founding anniversary of the Korean People’s Army (KPA) on February 9th, Kim designated ROK as an “archenemy” and proclaimed a policy to “occupy and subjugate” its territory if provoked. Subsequently, during the Ulji Freedom Shield (UFS), a biannual US-ROK military drill conducted from March 4th to 14th this year, North Korea revealed its invasion plan for South Korea. So today, I will explain North Korea’s invasion scenario for South Korea and assess the feasibility of this plan.

1. DPRK’s Invasion Scenario

Kim Jong Un's military visits over the 14 days starting March 4th show his invasion plan for South Korea. My prediction is not without basis—in fact, Kim Jong Un and Kim Yo Jong have disclosed their war visions and plans through various means over the past two years. My assumption rests on a comprehensive assessment of these actions.

The likely scenario would begin with an armed conflict at the Northern Limit Line (NLL) in the West Sea, an area North Korea has consistently turned into a conflict zone. However, this area is unequivocally our territorial waters. Unfortunately, while I firmly believe we cannot concede this territory, many outside of Korea perceive it as a conflict zone. Consequently, North Korea might believe they have grounds to justify their invasion of the NLL. With this justification, they could initiate armed conflict in the area, potentially escalating into a full-scale war.

If the war begins this way, around 340 long-range artillery cannons and multiple rocket launchers at the border could target Seoul. North Korea claims it can deliver up to 11,000 shots per hour, but this is unrealistic. I will elaborate on this in another episode. Anyway, they will use these long-range artilleries to strike Seoul and the surrounding metropolitan areas, then advance southward by mobilizing tanks and armored division.

The scenario so far is quite similar to the Korean War, but the difference lies in the potential use of low-yield nuclear weapons during the early stages of the war to gain strategic advantage. In April 2022, Kim Yo Jong explicitly stated that if ROK starts a military confrontation, DPRK will use nuclear weapons in the early stage of war to “eliminate the enemy’s armed forces at a strike,” indicating potential use of tactical nuclear weapons.

If war breaks out in this scenario, the ROK and US will implement a joint operation plan named “Operations Plan (OPLAN) 5015.” While this is currently being restructured into OPLAN 5022, it is expected that a significant number of US augmentation forces will be joining the war. To deter these augmentation forces, North Korea may utilize its intermediate-range ballistic missiles to target Guam or the United Nations Command-Rear Headquarters in Japan.

This is my basic outline of the DPRK’s invasion plan for South Korea, which I believe is confirmed by Kim Jong Un’s series of military visits during the UFS from March 4th to 14th.

He first visited a western operational training base of the KPA, tasked with attacking the NLL. And once the ROK-US exercise began, he reportedly oversaw the artillery firing drill of the KPA large combined units in charge of striking the metropolitan area. Then he guided the salvo drill of the sub-units of 600mm super-large multiple rocket launchers that can carry tactical nuclear warheads. He later supervised the ground jet test of a solid fuel engine for new-type intermediate-range hypersonic missiles capable of targeting Japan and Guam.

Kim Jong Un essentially visited the sites in the exact order of the scenario that I described.

2. The Feasibility of DPRK’s Invasion Plan

Now, let’s return to my initial question: Would DPRK really be able to invade the ROK? Are they determined to start a second Korean War? As some American policy groups favoring DPRK negotiations might question, does Kim Jong Un truly have the capability to wage war? And as repeatedly declared by Kim Jong Un and Kim Yo Jong, is a preemptive nuclear strike on South Korea within Pyongyang’s means?

In short, I believe it is impossible. Initiating a war would be a self-destructive action leading to the collapse of the North Korean regime.

Let me first explain North Korea’s nuclear doctrine. Fundamentally, developing nuclear weapons is futile without the means to deliver them. So DPRK has developed an intercontinental ballistic missile (ICBM) capable of carrying nuclear warheads to target the mainland United States. Then, from May 2019, they began diversifying the missile types capable of carrying nuclear weapons. This is when they developed a short-range ballistic missile, the KN-23. This trend in weapons development primarily aimed to bring South Korea within its striking range.

Such initiative clearly exposes North Korea’s challenges. Even as the DPRK continues to develop its missiles and nuclear weapons, I believe that securing the capability to effectively strike mainland US remains very difficult. Consequently, a stable “balance of terror” between the US and North Korea is extremely unlikely.

To understand the “balance of terror,” envision two nuclear states: North Korea and the US. If North Korea drops a nuclear bomb on the US mainland, the US would retaliate. A “balance of terror” is achieved only if North Korea has secured a second-strike capability to respond to the US counterattack. However, this scenario is highly improbable.

Conventionally, there are three elements of nuclear strategy: (1) deterrence to prevent use, (2) defense against an attack, and (3) counterstrike capabilities after an attack. DPRK is inferior to the US in all three aspects.

First of all, while we cannot be completely certain, we can detect North Korea’s nuclear use with a certain level of confidence. If anyone is interested, an article titled “The New Era of Counterforce” in International Security, published in 2017, elaborates on the US’ ability to detect and identify North Korean nuclear activities. According to the article, the US is capable of detecting North Korean activities to a significant extent. So if a nuclear attack is imminent and the US is certain of it, it can launch a preemptive strike on the DPRK.

The US has numerous options for a preemptive strike. Aside from high-yield and tactical nuclear weapons, they also have, for instance, the W76-2 Trident submarine-launched ballistic missile (SLBM) warhead. Because it is highly precise and low-yield, it can accurately target and neutralize the North Korean leadership. And being launched from a nuclear submarine, North Korea can never detect this.

If the United States were to fail in identifying an imminent North Korean strike, the missile defense systems stationed in the mainland and in Alaska that launch interceptor missiles would come into play. These will attempt to shoot down the incoming ICBM from North Korea.

If the missile defense plan were to fail and the US were to be attacked, do you think the US would remain passive and do nothing? No, the US would launch an “assured retaliation” by using its overwhelming nuclear power to annihilate North Korea.

The US has a variety of weapons at its disposal. For example, the Minuteman III, an ICBM stationed in California, can destroy Pyongyang in 3 to 4 minutes with its Multiple Independently targetable Reentry Vehicles (MIRV) system. Additionally, missiles like Trident II, which can be launched from nuclear ballistic missile submarines (SSBNs), are part of the US’ tactical nuclear arsenal. They are highly destructive and capable of destroying North Korea.

In other words, North Korea lacks the ability to execute a second-strike capability. Therefore, launching a war would inevitably be a suicidal act for North Korea.

3. North Korea’s Intent behind Nuclear Threats

Despite lacking a second-strike capability, North Korea continues this perplexing behavior, aiming to lower the nuclear use threshold by advocating for the integration of conventional and nuclear warfare.

Kim Jong Un and Kim Yo Jong have made this goal explicit over the past 2 to 3 years, and also declared through its newly amended nuclear force-building policy that it will use nuclear weapons against South Korea.

More recently, on December 31st last year, Kim Jong Un emphasized the intent to use nuclear weapons, stating that the DPRK will “put continuous spurs to the preparations for a great event [war] … by mobilizing all physical means and forces including nuclear forces in contingency.”

So why is North Korea doing this?

Countries that developed nuclear weapons early on often did so to compensate for their inferior conventional capabilities. By showcasing an aggressive nuclear doctrine and power, they aim to deter adversaries from initiating conventional warfare against them. Similarly, North Korea seeks to limit the military options available to the US and South Korea by emphasizing its readiness to deploy low-yield nuclear weapons during conventional warfare.

Although the context may differ, Putin is engaging in a similar strategy in Russia. Following the invasion of Ukraine, he has repeatedly threatened to use nuclear weapons if NATO member states intervene. This tactic aims to deter NATO involvement in Ukraine.

North Korea shares a similar intent. However, the most baffling difference is that it maintains this posture even though neither the ROK nor the US has shown any intention of attacking North Korea.

In my opinion, North Korea aims to demonstrate its readiness and ability to conduct limited warfare using low-yield nuclear weapons, thereby compelling the US and South Korea to acknowledge it as a de facto nuclear state. Its strategy is to avoid the risk of a large-scale retaliatory response from the US by developing nuclear capabilities targeted solely at South Korea. It does so by threatening the US without securing actual capability to follow through.

4. The Limits of North Korea’s Nuclear Doctrine

North Korea’s nuclear doctrine evidently has significant limitations. First and foremost, it is impossible to achieve specific political-military objectives through a limited attack using low-yield nuclear weapons.

Let me give you one example. North Korea frequently claims it will instill maximum terror at the onset of war by deploying a low-yield nuke on a less populated area of South Korea. In response to any US counteraction, it threatens to target the mainland US with ICBMs like the Hwasong-15, 17, or 18, aiming to deter further action. Following this, North Korea annexes a portion of ROK’s territory, declares victory, and initiates negotiation with the US and ROK.

In other words, North Korea seeks to accomplish its political-military goals through limited warfare, without escalating into a full-scale nuclear conflict.

I will challenge this scenario.

First of all, North Korea’s tactical nuclear strike will result in an immediate escalation to total war. The reason is that missiles like the KN-23 and KN-24 cannot effectively target South Korea using only a few projectiles, as both the ROK and the US possess missile defense systems capable of intercepting the missiles to some degree. Therefore, North Korea would have to launch multiple tactical nuclear warheads simultaneously.

However, launching such a significant number of missiles would be tantamount to initiating a total war. Additionally, to execute a major assault in South Korea, larger warheads are necessary. Small warheads would fall short of achieving the impact North Korea intends. Also, a nuclear attack will inevitably result in a substantial civilian casualty, given the dense population of most South Korean cities. Moreover, North Korea faces a significant risk in attacking strategic military bases, as many are jointly operated by the ROK and the US. In essence, any nuclear aggression from North Korea would precipitate total war.

If North Korea were to launch a nuclear missile, South Korea would initiate a counter-response with its "three-axis system." For instance, South Korea possesses the Hyunmoo-5, which can carry the heaviest warhead among conventional ballistic missiles, along with other missiles designed for high-precision strikes. These missiles enable precision-guided operations aimed at decapitating the North Korean leadership. Assets like the F-35 stealth fighter jets can operate undetected by DPRK’s radar systems. All these capabilities could be mobilized in a total war scenario to target North Korea's operational headquarters.

On another note, would the US remain passive? Consider the scenario where North Korea launches a small, low-yield nuclear weapon and then threatens to attack the US mainland as a deterrent. Let's ponder this situation, which is central to the concept of extended deterrence.

Given that North Korea is attempting to threaten the US with an attack on its mainland, do you believe the US would step back, or would it respond with significant retaliation against the DPRK to eliminate the threat? The latter scenario is far more probable.

Reflecting on the war history and nuclear strategy of the US, it is clear that if the US genuinely perceives its mainland to be under threat of invasion, it would likely resort to large-scale retaliation with high-yield nuclear weapons to neutralize North Korea's nuclear capabilities. This perspective is shared by numerous strategists in the US as well.

In sum, North Korea initiating a conventional warfare and launching a low-yield nuclear weapon would essentially amount to total war. South Korea and the US possess second-strike capabilities, and the deployment of US nuclear weapons may also be on the table. Therefore, unless Kim Jong Un opts for the irrational path of self-destruction, he cannot commence a war.

Who do you think stands to lose the most in a war? The wealthiest individual on the Korean Peninsula, Kim Jong Un, also wields absolute power over North Korea. Given his position, it is improbable he would willingly enter a conflict with a foreseeable loss.

This is why I am convinced that North Korea will not initiate war, despite its recent demonstrations of invasion scenarios and nuclear threats towards South Korea.

■ Won Gon PARK is the Chair of EAI Center for North Korea Studies and a Professor of North Korean Studies at Ewha Womans University.

■ Typeset by: Jisoo Park, Research Associate
    For inquiries: 02 2277 1683 (ext. 208) | jspark@eai.or.kr