Is South Korea ready to go it alone on defense?

Beneath the reassuring rhetoric from Seoul and Washington, the U.S.-South Korea alliance and South Korea's own military capabilities are under increasing pressure from the changing geopolitical climate and North Korea's nuclear and missile threats.

The Korea JoongAng Daily examines the economic, political and military challenges facing Korea as the United States makes big moves to protect its economic interests. Caught between the United States and China, the country is seeking to maintain a balance without being locked out of either economy. This involves intense lobbying and some tough decisions for Korean companies, some of which are dependent on China for the manufacturing of key products. This is the last in a three-part series. -Ed.

Forged in the crucible of the 1950-53 Korean War, the military alliance between Seoul and Washington has held on through numerous crises, including developments in North Korea's nuclear and missile programs, Cold War-era disagreements over South Korea's dictatorship and brief nuclear ambitions, as well as episodic reductions of the U.S. military presence on the peninsula.

The alliance has been underpinned by a pair of complementary military interests: Seoul's need for a defense guarantor in a neighborhood enveloped by superpowers, and Uncle Sam's desire to maintain a physical check on powerful foes that could encroach on U.S. domination of the Pacific.

Faced with the advancing nature of the North Korean threat, Seoul and Washington appear to be doubling down on their alliance, with South Korean President Yoon Suk-yeol and U.S. President Joe Biden agreeing at their first summit in May to coordinate the deployment of U.S. strategic assets to the Korean Peninsula, while U.S. officials on numerous occasions have described their country's commitment to South Korea's defense as "ironclad."

But beneath the reassuring rhetoric, the two countries' alliance, and South Korea's own military capabilities, are under evolving and increasing pressure from the changing geopolitical climate and North Korea's nuclear and missile threats.

As Washington strives to maintain military and technological superiority over Beijing, it also strains South Korea's longstanding strategy of relying on the United States for security and on China for trade to support its economy. By demanding that Seoul fall in line with its supply chain reorganization, which is designed to prevent China from developing cutting-edge semiconductor technology, it could deprive South Korea of its largest market for chips.

While encroaching on Seoul's economic interests, Washington under Biden is also signaling more strongly that the United States would intervene in a hypothetical conflict over Taiwan, despite efforts by the U.S. State Department to maintain official ambiguity about the U.S. response in that scenario.

In such an event, South Korea's alliance with the United States, which is precisely designed to shield the country from war, could drag it into a conflict.

If forced to choose between its economic interests in China and its U.S. alliance — or the worst-case scenario in which it is forced to support U.S. military action over Taiwan — Seoul may have to question its security arrangement with Washington and evaluate the state of its own defenses.

An alliance at crossroads?

Before this question is posed, it is important to note that Washington's military alliances in general have held steady, and that neither the United States nor South Korea have expressed interest in ending their current arrangement.

"The purpose of the South Korea-U.S. alliance is to reinforce the security of South Korea — so why would Seoul end it?" asks Antoine Bondaz, director of the Korea Program for the Paris-based Foundation for Strategic Research.

Indeed, as the ongoing Russian invasion of Ukraine makes apparent, the difference between a country having a defense treaty with a global superpower such as the United States and being left to fend for itself is hard to understate.

For the South Korea-U.S. alliance to come to an end, Bondaz suggests the critical condition that would have to be met is that South Korea no longer needs U.S. help to defend itself — but there are other dynamics in play.

For decades, the U.S. military presence in South Korea was backed by the assumption that the United States could mount a conventional as well as nuclear attack on North Korea without risk to the U.S. homeland.

But with the North demonstrating it can launch missiles that could travel a range between 6,700 (4,163 miles) and 8,000 kilometers — well beyond the 5,500 kilometer cutoff that the United States uses for classifying "intercontinental" — there is growing concern that Washington could be constrained in its response if hostilities break out once again on the Korean Peninsula.

"With North Korea developing the ability to strike the United States, Seoul and Tokyo may soon wonder whether the United States would truly give up New York or Los Angeles for them," wrote Ankit Panda, a senior fellow in the Nuclear Policy Program at the Carnegie Endowment for International Peace, in a 2017 article for the Texas National Security Review.

Here, Panda refers to "decoupling," a Cold War-era term referring to the potential dissolution of alliances when their underlying security guarantees becoming untenable.

But while Panda says the qualitative changes in North Korea's missile arsenal aren't "game changers," he admits that "reassuring U.S. allies in Northeast Asia will continue to be challenging as long as North Korea maintains its robust nuclear capabilities."

Kim Jung-sup, a senior research fellow at the Sejong Institute, notes that decoupling as a result of increases in the range of North Korea's missiles is unlikely to occur precisely because the United States has long been accustomed to that kind of risk.

"The United States faced down a nuclear threat to its own territory throughout the Cold War — of course, some countries like Britain and France developed their own nuclear deterrents because they weren't certain of the U.S. commitment, but that pledge held steady throughout the period," Kim said.

"Our alliance with the United States ultimately comes down to a question of trust, and I don't think decoupling is likely without a loss of South Korean faith in the U.S. commitment," he added.

But while the United States has publicly reassured South Korea of the extension of its nuclear deterrent — the so-called "nuclear umbrella" — this does not mean there are no doubts about the effectiveness of current arrangements, especially the location of U.S. nuclear weapons.

Yang Uk, an associate research fellow at the Asan Institute, pointed to logistical complications in the allies' cooperation as a result of the advancing North Korean nuclear threat.

"Conditions on the Korean Peninsula have certainly changed – for example, there are more questions than before as to whether the United States can employ its nuclear weapons in time, given that Kim is threatening to deploy and deputize the use of nuclear weapons to North Korea's frontline tactical nuclear operations units," Yang said.

According to recent reports by Pyongyang's state-run Korean Central News Agency (KCNA), the North appears to be shifting the focus of its nuclear weapons program towards tactical nuclear weapons and away from strategic nuclear weapons.

Strategic nuclear weapons are aimed at destroying wide areas, such as entire cities, while tactical nuclear weapons have a comparatively smaller explosive yield and are designed to attack military targets and destroy a limited area.

There is also the question of how South Korea would view its treaty alliance with the United States if the latter should decide to intervene to prevent a forceful takeover of self-governing Taiwan by China, which enforced a mock naval blockade around the island after U.S. Speaker of the House Nancy Pelosi's visit to Taipei in August.

"Korea faces a dilemma [in the case of Taiwan] since it doesn't want to be dragged into an unwanted conflict, but it also doesn't want to be abandoned because it reneged on its alliance commitments," Kim said, suggesting that one way Korea could balance these two objectives "is by providing materiel and logistical support for U.S. military action — that is, supporting military action at a distance from the main battle theaters."

But there remains a risk that Korea would not be able to maintain such a balance if a hypothetical war over Taiwan spreads to its territory.

"If the Chinese military were to launch an attack on United States Forces Korea (USFK) bases here in South Korea, would we treat it as an attack on our territory?" asks Yang, adding that any conflict over Taiwan "would raise all sorts of questions over Korea's level of involvement."

A cat-and-mouse game

Military experts widely agree that in conventional terms, South Korea's military dominates its northern rival.

"In strictly conventional terms, South Korea is definitely capable of fighting a war without the aid of the United States — it's just that from the North Korean perspective, the South would be a less formidable target if it doesn't have U.S. support," says Yang. "There is just no comparison between the two Koreas' conventional forces, especially their air forces and navies."

Even where the North appears to have a numerical troop advantage, Yang says, the South Korean military is better prepared to fight a conventional war.

"There is a disparity between the size of the two Koreas' land armies, with the North having almost twice as many active-duty soldiers as the South at any given time because of demographic trends in South Korea and the much longer North Korean military service period," Yang acknowledged.

"That being said, South Korea has a deeper pool of men and reservists to fight in a hypothetical conflict, because our population is almost twice the size of North Korea's."

The big caveat in these comparisons is that they do not factor in the North's nuclear weapons.

Seoul's current deterrence-through-punishment strategy vis-à-vis nuclear-armed Pyongyang is composed of three components: a Kill Chain, which relies on surface-to-surface missiles and earth-penetrating weapons to destroy North Korean missile-launching capabilities before missiles can be fired; Korea Missile Defense (KMD), which would destroy incoming missiles mid-air with a mixture of Patriot missiles and Korean medium-range surface-to-air (KM-SAM) missiles; and the Korea Massive Punishment and Retaliation (KMPR) system, which would target individuals in North Korea's leadership and military command.

But KMPR, as Yang points out, is based on the assumption that the United States would use its nuclear weapons after North Korea uses, or attempts to use, its nuclear arsenal.

"KMPR does not work if it is put into action without nuclear weapons, so by extension it requires coordinating U.S. action," Yang says.

Kwon Yong-soo, a senior research fellow at the Korea Institute for Military Affairs (KIMA) and a former professor at the Korea National Defense University, goes so far as to rule out the idea of the South attempting to defend itself with solely conventional means.

"To use the term 'independent defense capabilities' to refer to a country faced with a nuclear-armed adversary is inappropriate," Kwon says. "Dealing with the North Korean nuclear threat requires a comprehensive security strategy that entails not only military and defense cooperation, but also political, diplomatic and economic coordination" with the United States.

But even with the U.S. nuclear deterrent in play, Seoul's K-3 strategy may not be sufficient, according to Bondaz.

Referring to the KMD component of the plan, Bondaz says, "Most studies underestimate the significance of North Korean missile technology advances in the last five years as demonstrated by newly tested [North Korean] short-range missiles such as the KN-23 and KN-24, as well as these missiles' precision and their ability to penetrate antimissile defenses."

These missiles do not fly in the usual parabolic trajectories of ballistic missiles, but can perform "pull-up" maneuvers at lower altitudes as they approach their targets, thereby evading missile defense system that target them in their descent phase.

Retired Lt. Col. Kim Yeoul-soo, who is a senior researcher at KIMA, is in agreement with Bondaz, saying, "The current range of KM-SAM systems is approximately 30-40 kilometers, while the operational range of Pac-3 systems is 40 kilometers, so our antimissile defense systems would have to increase in range and become more varied to target different types of North Korean missiles."

But Panda argues South Korea faces a broader problem than North Korea's increasingly maneuverable missiles."Simply put, even an adversary like North Korea that's quite resource-constrained can cost-effectively stress missile defense systems by simply building more missiles than the defender — South Korea in this case — has interceptors," he says, adding, "Both qualitative and quantitative missile defense defeat strategies are at play for North Korea."

Yang also cautions that the quest for an infallible missile defense system would be misplaced.

"There is no such thing as a perfect, impenetrable missile defense system," he says. "The K-3 strategy was drawn up when we assumed the North would use Scud-type missiles in the event of war, but they've moved onto Iskander-type missiles since 2017, and we can only assume they will continue diversifying their missile arsenal, which would lead to constant cycle of the two sides trying to catch up with one another, then trying to one-up the other's weapons."

Kim Jung-sup argues that while antimissile defense systems are important, South Korea needs to focus on the credibility of its retaliatory response to preclude a North Korean attack.

"Since the attacker firing missiles usually holds the advantage over a defender equipped with interceptive capabilities, the correct approach to missile defense is to enhance our own missile deterrent capabilities — that is, to threaten consequences so severe in response to an attack that it would deter a potential attacker in the first place," he said.

"South Korea should not only improve its Hyunmoo ballistic missiles, but also the explosive and penetrative power of its missile warheads to destroy underground North Korea facilities and enhance its satellite reconnaissance and surveillance capabilities."

Still others, like Kwon, argue that the use of weapons systems in the K-3 plan should be integrated with other combat forces and fighting knowledge.

"We need to seriously reconsider our contingency plans as it becomes more likely that North Korea will use a variety of different kinds of missiles equipped with tactical nuclear warheads," Kwon says. "Instead of focusing solely on weapons systems, we absolutely must enhance our fighting capabilities by adapting new strategies and integrating our combat forces, as well as increasing training for our weapons systems' operators."

The nuclear elephant in the room

One area where all experts are in agreement is that no South Korean response strategy to a North Korean attack would be effective without nuclear weapons — and almost all cautioned that Seoul would have to ponder many other options before considering developing its own nuclear deterrent.

But their advice doesn't jibe with South Korean public opinion. According to a survey included in a February report by the Chicago Council on Global Affairs, 71 percent of respondents said Seoul should develop its own nuclear weapons.

"It's because South Koreans are ill at ease with the current situation that our politicians talk about getting the United States to deploy its tactical nuclear weapons to the peninsula," says Kim Yeoul-soo. "But nuclearization wouldn't happen overnight. There would be several options we would examine, beginning with deploying U.S. tactical nuclear weapons or sharing control of the U.S. nuclear deterrent, before we progressed to a discussion about developing our independent nuclear deterrent."

Kim Jung-sup highlighted the risk that nuclear weapons development could actually undermine and not bolster Seoul's security.

"The United States is currently committed to the extension of its nuclear deterrent to its East Asian allies, but if we were to decide to develop our own nuclear deterrent, it could jeopardize the U.S. pledge to protect South Korea," he said.

Kim also highlighted the fact that the U.S. nuclear umbrella is contingent on a continuing commitment by Washington.

"If there were to be another president like Donald Trump — that is, another president or change in the U.S. administration that were to pursue isolationism — that would definitely give cause to reconsider our current nonproliferation stance, especially if it brought the credibility of the U.S. commitment to South Korea's defense in doubt," he acknowledged.

Yang points out "the economic and security consequences of withdrawing from the international nonproliferation regime could be very severe," and that South Korea "ought to consider other options, like participating in planning for the use of U.S. nuclear weapons in the way NATO does nuclear sharing, before going down the road of nuclear weapons development."

Kwon highlighted the diplomatic ramifications of Seoul pursuing nuclear weapons.

"If we were to develop our own nuclear deterrent, we would not only be endangering the global nuclear nonproliferation regime, but also undermining the legal basis for sanctions against North Korea," he said. "If we want to change the current status quo, we must not only strengthen our alliance with the United States, but also work to foster trust with China. Any changes will need to rely on diplomatic goodwill and be phased in a way that is appropriate at the moment."

Panda, who described himself as "not fatalistic" about South Korean proliferation, said, "In practice, going nuclear will require South Korea to make many compromises that will affect its prosperity and security. It's not at all obvious that nuclear weapons will solve South Korea's security problems too — many problems Seoul faces now could even grow worse if it chose to develop nuclear weapons." Bondaz cautioned that while South Korea could theoretically withdraw from the Treaty on the Non-Proliferation of Nuclear Weapons (NPT) in a legal manner, it would have to ponder several important questions.

"One question Seoul should ask itself before it decides to pursue nuclear weapons is whether the West is sufficiently dependent on South Korea to not sanction it, even if it withdraws from the treaty," Bondaz says.

"We can imagine that some in South Korea believe that the global economy is so dependent on the country it would never be sanctioned by the United States — but I would say the principal problem of South Korea going nuclear is not the United States, but China," he added.

"What would be the reaction of China if South Korea goes nuclear?" he asked.

BY MICHAEL LEE [lee.junhyuk@joongang.co.kr]