SEOUL — President Yoon Suk Yeol of South Korea said for the first time on Wednesday that if North Korea’s nuclear threat grows, South Korea would consider building nuclear weapons of its own or ask the United States to redeploy them on the Korean Peninsula.
Speaking during a joint policy briefing by his defense and foreign ministries on Wednesday, Mr. Yoon was quick to add that building nuclear weapons was not yet an official policy. He stressed that South Korea would for now deal with North Korea’s nuclear threat by strengthening its alliance with the United States.
Such a policy includes finding ways to increase the reliability of Washington’s commitment to protect its ally with all of its defense capabilities, including nuclear weapons.
Mr. Yoon’s comments marked the first time since the United States withdrew all of its nuclear weapons from the South in 1991 that a South Korean president officially mentioned arming the country with nuclear weapons. Washington removed its nuclear weapons from South Korea as part of its global nuclear arms reduction efforts.
“It’s possible that the problem gets worse and our country will introduce tactical nuclear weapons or build them on our own,” said Mr. Yoon, according to a transcript of his comments released by his office. “If that’s the case, we can have our own nuclear weapons pretty quickly, given our scientific and technological capabilities.”
South Korea is a signatory of the Nuclear Nonproliferation Treaty, or NPT, which bans the country from seeking nuclear weapons. It also signed a joint declaration with North Korea in 1991 in which both Koreas agreed not to “test, manufacture, produce, receive, possess, store, deploy or use nuclear weapons.”
But North Korea has reneged on the agreement by conducting six nuclear tests since 2006. Years of negotiations have failed to remove a single nuclear warhead in the North. (American and South Korean officials say that North Korea could conduct another nuclear test, its seventh, at any moment.)
As North Korea vowed to expand its nuclear arsenal and threatened to use it against the South in recent months, voices have grown in South Korea — among analysts and within Mr. Yoon’s conservative ruling People Power Party — calling for Seoul to reconsider a nuclear option.
Mr. Yoon’s comments this week were likely to fuel such discussions. Opinion surveys in recent years have shown that a majority of South Koreans supported the United States redeploying nuclear weapons to the South or for their country to build an arsenal of its own.
North Korea’s Missile Tests
An increase in activity. In recent months, North Korea has conducted several missile tests, hinting at an increasingly defiant attitude toward countries that oppose its growing military arsenal. Here’s what to know:
U.N. resolutions. Tensions on the Korean Peninsula started rising in 2017, when North Korea tested three intercontinental ballistic missiles and conducted a nuclear test. The United Nations imposed sanctions, and Pyongyang stopped testing nuclear and long-range missiles for a time.
Failed diplomacy. Former President Donald Trump met with Kim Jong-un, the North Korean leader, three times between 2018 and 2019, hoping to reach a deal on North Korea’s nuclear and missile programs. After the talks broke down, North Korea resumed missile testing.
An escalation. North Korea started a new round of testing in September 2021 after a six-month hiatus. It subsequently completed several tests, including the firing of multiple intermediate-range and intercontinental ballistic missiles, that violated the 2017 U.N. resolutions.
New provocations. Mr. Kim has launched a record number of missiles and focused on developing new ones in 2022. The North Korean leader has said that a “neo-Cold War” is emerging and has vowed to expand his country’s nuclear capabilities against South Korea “exponentially.”
Policymakers in Seoul have disavowed the option for decades, arguing that the so-called nuclear-umbrella protection from the United States would keep the country safe from North Korea.
“President Yoon’s comment could turn out to be a watershed moment in the history of South Korea’s national security,” said Cheon Seong-whun, a former head of the Korea Institute for National Unification, a government-funded research think tank in Seoul. ”It could shift its paradigm in how to deal with the North Korean nuclear threat.”
Calls for nuclear weapons have bubbled up in South Korea over the decades, but they have never gained traction beyond the occasional analyst and right-wing politicians.
Under its former military dictator Park Chung-hee, South Korea embarked on a covert nuclear weapons program in the 1970s, when the United States began reducing its military presence in the South, making its people feel vulnerable to North Korean attacks. Washington forced him to abandon the program, promising to keep the ally under its nuclear umbrella.
Washington still keeps 28,500 American troops in South Korea as the symbol of the alliance. But in recent months, North Korea has continued testing missiles, some of which were designed to deliver nuclear warheads to the South. Many South Koreans have questioned whether the United States would stop North Korea from attacking their country, especially at the risk of leaving American cities and military bases in the Asia-Pacific region more vulnerable to a nuclear attack. Washington’s repeated promise to protect its ally — with its own nuclear weapons, if necessary — has not dissipated such fear.
In its 2022 Nuclear Posture Review, a document that outlines Washington’s nuclear policy for the next five to 10 years, the Pentagon itself noted the “deterrence dilemmas” that the North posed to the United States. “A crisis or conflict on the Korean Peninsula could involve a number of nuclear-armed actors, raising the risk of broader conflict,” it said.
“If South Korea possesses nuclear weapons, the United States will not need to ask whether it should use its own nuclear weapons to defend its ally, and the alliance will never be put to a test,” said Cheong Seong-chang, a senior analyst at the Sejong Institute in South Korea. “If South Korea owns nuclear weapons, the U.S. will actually become safer.”
By declaring an intention to arm itself with nuclear weapons, South Korea could force North Korea to rethink its own nuclear weapons program and possibly prompt China to put pressure Pyongyang to roll back its program, Mr. Cheong said. China has long feared a regional nuclear arms race in East Asia.
South Korea would need to quit the NPT to build its own arsenal. Analysts said that quitting the NPT would be too risky for the South because it could trigger international sanctions.
Some lawmakers affiliated with Mr. Yoon’s party and analysts like Mr. Cheon want the United States to reintroduce American nuclear weapons to the South and forge a nuclear-sharing agreement with Seoul, similar to the one in which NATO aircraft would be allowed to carry American nuclear weapons in wartime.
The American Embassy had no immediate comment on Mr. Yoon’s statement. Washington’s official policy is to make the Korean Peninsula free of nuclear weapons, fearing that if Seoul were to build nuclear weapons, it could trigger a regional arms race and eliminate any hope of ridding North Korea of its nuclear weapons.
Mr. Yoon himself reiterated on Thursday that his country remained committed to the NPT, at least for now. He said on Wednesday — and his Defense Ministry reiterated on Thursday — that the more “realistic means” of countering the North Korean threat would be through joint deterrence with the United States.
His government said the allies will introduce tabletop exercises from next month to test their combined capabilities to deal with a North Korean nuclear attack and to help reassure Washington’s commitment to its ally. Mr. Yoon also said his military will boost its own “massive punishment and retaliation” program, arming itself with more powerful missiles and other conventional weapons to threaten the North’s leadership.
Tensions have been on the rise in Korea in recent weeks, as Mr. Yoon’s government responded to the North’s provocations with its own escalatory steps, like dispatching fighter jets in response to drones from the North.
“We must squash the North’s desire to provoke,” he said on Wednesday.