Argument

The U.S. Will Trade Seattle for Seoul

Cold War archives reveal why South Korea doesn’t need its own nuclear weapons to deter the North.

nuclear-deterrance-us-korea-soviet-jfk-illustration-2022
nuclear-deterrance-us-korea-soviet-jfk-illustration-2022
Foreign Policy illustration/Getty Images and archival document
By , a defense analyst and a former staffer on the U.S. House Foreign Affairs Committee.

As if the world weren’t messy enough, North Korean leader Kim Jong Un is back to his usual antics with a flurry of recent missile tests, prompting various responses from the United States, South Korea, and Japan. Adding a new twist to a familiar story, North Korea flew bombers and fighter jets close to South Korean airspace, forcing Seoul to scramble its own aircraft.

In truth, although it has faded from global headlines, North Korea’s nuclear advances have quietly reshaped regional security dynamics since the “fire and fury” days of 2017. This is especially true when it comes to the question of whether South Korea should build its own nuclear weapons. The South Korean public has long supported this option: Recent polls have found that 71 percent of South Koreans favor a nuclear capability.

They are increasingly joined by South Korean leaders who question whether the United States will come to Seoul’s defense now that North Korean missiles can reportedly reach any U.S. city. As Lee Baek-soon, a former South Korean ambassador to Australia, put it, “the reliability of [the U.S.] nuclear umbrella is in question as North Korea possesses intercontinental ballistic missiles capable of striking the U.S. mainland.”

As if the world weren’t messy enough, North Korean leader Kim Jong Un is back to his usual antics with a flurry of recent missile tests, prompting various responses from the United States, South Korea, and Japan. Adding a new twist to a familiar story, North Korea flew bombers and fighter jets close to South Korean airspace, forcing Seoul to scramble its own aircraft.

In truth, although it has faded from global headlines, North Korea’s nuclear advances have quietly reshaped regional security dynamics since the “fire and fury” days of 2017. This is especially true when it comes to the question of whether South Korea should build its own nuclear weapons. The South Korean public has long supported this option: Recent polls have found that 71 percent of South Koreans favor a nuclear capability.

They are increasingly joined by South Korean leaders who question whether the United States will come to Seoul’s defense now that North Korean missiles can reportedly reach any U.S. city. As Lee Baek-soon, a former South Korean ambassador to Australia, put it, “the reliability of [the U.S.] nuclear umbrella is in question as North Korea possesses intercontinental ballistic missiles capable of striking the U.S. mainland.”

Other South Korean politicians and military leaders are even more explicit. “Either American extended nuclear deterrence is formidable and credible, or South Korea acquires its own nuclear weapons,” Chun In-bum, a former commander of South Korea’s special forces, told the Financial Times, before adding, “I have never doubted an American soldier. But I would be foolish to place my nation’s security in the hands of an American politician.” A growing number of Western analysts seem to agree.

However, the arguments supporting this move all rely on historical examples of nuclear deterrence from another place and another time: a flawed understanding of the security dynamics of Cold War Europe. A closer look at this context demonstrates that South Korea doesn’t need its own arsenal—and that acquiring one will actually harm U.S. interests in the short and long term.


Proponents of a nuclear South Korea argue that its security challenges are analogous to those of U.S. allies in Cold War Europe. When the Soviet Union acquired long-range nuclear missiles, European leaders questioned the United States’ willingness to defend them. As French President Charles de Gaulle famously quipped to U.S. President John F. Kennedy in 1961, would the United States really be willing to trade New York for Paris? Writing in these pages, Robert E. Kelly argues, “That same logic is at work in East Asia today. The United States will not sacrifice ‘Los Angeles for Seoul.’” Other American and South Korean analysts make the same analogy.

As I discuss in my book, Atomic Friends: How America Deals With Nuclear-Armed Allies, the two situations are not as comparable as they may seem on the surface. During the Cold War, NATO believed it couldn’t mount a conventional defense of Europe. Instead, the alliance’s war plans required the United States to use nuclear weapons to offset Moscow’s conventional superiority. Once the Soviet Union gained the capability to attack the United States with nuclear weapons, European leaders questioned whether a U.S. president would be willing to use the bomb to defeat a Soviet conventional attack.

In explaining what he meant by trading New York for Paris, according to a summary of the conversation sent to U.S. Secretary of State Dean Rusk, de Gaulle told Kennedy that his concern was the United States would not be the “first to use nuclear weapons if Soviets launch [a] purely conventional attack.”

The concerns on the Korean Peninsula today are quite different. The United States and South Korea enjoy conventional superiority over North Korea’s military. Seoul alone spends about 10 times as much on its military as Pyongyang, and the technology gap is even wider. Unlike in Cold War Europe, U.S. and South Korean forces could repel a purely conventional invasion.

Therefore, questions about U.S. credibility on the Korean Peninsula are premised on two conditions. First, if North Korea invades, will the United States mount a conventional defense of South Korea knowing Kim could resort to nuclear weapons to forestall defeat on the battlefield? Second, would the United States be willing to use nuclear weapons to retaliate against North Korean nuclear attacks on South Korea?

With a unified NATO command, and millions of U.S. troops on the front lines, European officials knew the United States would fight an invading Soviet force. The same is true in Korea today.

European leaders did not doubt either of these things during the Cold War, and South Korean officials shouldn’t today. With a unified NATO command, and millions of U.S. troops on the front lines, European officials knew the United States would inevitably fight an invading Soviet force using its conventional capabilities. The same is true in Korea today, given the unified command and large U.S. troop presence there.

Many are concerned that the United States might withdraw from the Korean Peninsula if Donald Trump, or someone with similar views, becomes president again. This is understandable, but it ignores the nearly unanimous bipartisan support for maintaining a U.S. troop presence in South Korea. During Trump’s presidency, Republican members of Congress were consistently willing to stand up to him on this issue.

In fact, Congress put a provision in its annual defense policy legislation forbidding the president from withdrawing from South Korea. There is a robust bipartisan consensus that the Indo-Pacific is America’s priority region, which provides an even stronger basis to support maintaining a large U.S. troop presence on the Korean Peninsula in the future.

European leaders also believed the United States would use nuclear weapons if the Soviet Union launched nuclear attacks on Western Europe. According to a memo of Kennedy’s visit to Paris in 1961, de Gaulle himself said he “fully believes that if the Soviets start atomic warfare, the US will retaliate.” So should South Korean leaders today. If North Korea used nuclear weapons against South Korea, U.S. troops on the peninsula and Americans living there would be caught in the crossfire.

A document that chronicles U.S. President John F. Kennedy’s conversation with French President Charles de Gaulle in Paris in 1961.
A document that chronicles U.S. President John F. Kennedy’s conversation with French President Charles de Gaulle in Paris in 1961.

The first two pages of a document that chronicles U.S. President John F. Kennedy’s conversation with French President Charles de Gaulle at the Élysée Palace in Paris on the morning of June 2, 1961. Read the full memo.

The United States is hardly known for acting with restraint when its military or citizens are attacked. The tragedies of Pearl Harbor and 9/11—in which thousands of Americans were killed—would numerically pale in comparison to Kim using nuclear weapons in South Korea, where tens of thousands of U.S. troops and civilians would almost certainly be killed.

Any U.S. president would be under at least as much pressure to retaliate as Franklin D. Roosevelt and George W. Bush were in their respective historical contexts. The bottom line is, whether resorting to the nuclear arsenal or not, U.S. political leaders couldn’t allow Kim or his regime to survive if it used nuclear weapons against South Korea.

Managing extended deterrence will always be an incredibly fickle, uncertain business. To do it successfully, the United States must continuously make its commitments clear to both South Korea and North Korea, just as it did with NATO and the Soviet Union during the Cold War. Compared with deterring a conventional attack on West Germany using nuclear weapons during the Cold War, deterring a nuclear attack from North Korea today is a far easier task. South Korean defense planners should feel some level of assurance from this, combined with the United States’ strong and growing interest in their country’s security.

Managing extended deterrence will always be an incredibly fickle, uncertain business.

Besides suggesting that South Korea should trust the United States’ security guarantee, Cold War Europe also shows the dangers that a South Korean nuclear weapons program could pose to the United States. Once Britain and France acquired the bomb, they both slashed their conventional forces—decisions that London and Paris explicitly tied to their possession of nuclear arms.

With nuclear forces ensuring their defense, British and French leaders wanted to spend less on guns and more on butter. Washington chafed at British and French military cuts because they forced the United States to shoulder a greater share of the defense burden. Not much has changed since, as the United States similarly needs its Indo-Pacific allies to strengthen their conventional forces instead of allowing them to atrophy to create redundant strategic arsenals.

An even more alarming possibility is that a nuclear-armed South Korea could order U.S. forces off its territory. Once France had an operational nuclear deterrent, de Gaulle withdrew Paris from NATO’s unified command and removed U.S. and NATO troops from French territory. De Gaulle tied this decision to France having the bomb, but it was also rooted in his preexisting views on French nationalism, the value of alliances, and U.S. involvement in European affairs.

Notably, the South Korean left has similar views on many of these issues. Internationally, South Korean liberals and progressives are best known for having dovish views toward North Korea. But they are also defense hawks who favor more strategic autonomy, which is partly based on a form of Korean nationalism. It’s hardly unthinkable that, once secure with a nuclear arsenal, a left-leaning South Korean administration would assert strategic autonomy by removing U.S. troops from the country, much as France did.

Losing access to South Korea would be a devastating blow to the United States’ military posture in the Indo-Pacific and far more impactful than de Gaulle’s action. NATO’s multilateral nature allowed Washington to relocate its forces to Belgium and Germany, but this option would not be available in today’s Indo-Pacific, given the U.S. “hub and spoke” alliance system in the region. Put simply, if Seoul demanded a U.S. withdrawal, these forces could not be easily relocated somewhere else in the region.

Despite today’s unprecedented North Korean nuclear threat, a closer look at Cold War history suggests South Korean nuclear weapons aren’t necessary to deter Kim. The U.S.-South Korean alliance, backstopped by the U.S. nuclear deterrent, is capable of defending South Korea.

Furthermore, as it deepens its engagement in the Indo-Pacific, the United States will have an even greater incentive to maintain its presence in South Korea. Despite this assurance, the alliance should carefully heed the lessons of history. If Seoul were to one day acquire nuclear weapons, it is unlikely to make South Korea or the United States safer. On the contrary, doing so would undermine their alliance and weaken the United States’ military posture in the Indo-Pacific.

Zachary Keck is a defense analyst and a former staffer on the U.S. House Foreign Affairs Committee. He is the author of Atomic Friends: How America Deals With Nuclear-Armed Allies. The views expressed in this article are those of the author and do not reflect the official policy or position of the U.S. Defense Department or the U.S. government. Twitter: @ZacharyKeck

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