Explainer: South Korea’s nuclear dilemma: Would U.S. trade Seattle for Seoul?

On Wednesday, U.S. President Joe Biden will meet with South Korean leader Yoon Suk Yeol to reassure South Koreans that the nuclear umbrella will defend them from North Korea.

With North Korean missiles now threatening the US, an old Cold War conundrum has resurfaced: would the US risk nuclear retaliation against itself to defend an ally?

WHAT’S WORRYING SOUTH KOREA?

North Korea would risk severe U.S. retaliation if it attacked South Korea with nuclear weapons, under U.S. “extended deterrence” protection.

After Pyongyang detonated a nuclear bomb in 2006, this was a credible danger because North Korea had few bombs and little ability to export them.

However, it now has intercontinental ballistic missiles (ICBMs) that may reach U.S. cities, making defending South Korea more expensive.

After former President Donald Trump questioned the value of the South Korean alliance, many South Koreans now support their country developing nuclear weapons.

Last month, 64% of South Koreans supported this, something the Biden administration opposes.

South Korea’s options?
Yoon campaigned to redeploy U.S. tactical nuclear weapons in South Korea and maybe “nuclear sharing,” or shared command of U.S. weapons. He suggested in January that Seoul might soon create a nuclear weapons given its scientific expertise.

Yoon retracted his comments about a South Korean bomb and said his administration was dedicated to the nuclear non-proliferation pact (NPT).

His remarks have sparked a debate that one former senior U.S. defense official said may mainstream a South Korean nuclear arsenal.

BIDEN-Yoon Summit Expectations
Senior U.S. sources said Biden will pledge “substantial” actions to reinforce extended deterrence to offset such views. One official stated a “Washington Declaration” will create a “Nuclear Consultative Group” to allow South Korea “a voice in those deliberations” on U.S. major contingency plans.

Another remarked, “Our absolute and enduring commitment to provide extended deterrence to (South Korea), including, as necessary, a decisive response,” was the goal.

The leaders will announce regular strategic asset deployments, including the first U.S. nuclear ballistic-missile submarine visit to South Korea since the early 1980s, to demonstrate deterrence.

The officials emphasised that there was “no vision” of restoring U.S. nuclear weapons to the Korean peninsula and that the U.S. president had exclusive control over their use, while Seoul would reaffirm its NPT commitment and non-nuclear status.

WHAT WOULD NUCLEAR SOUTH KOREA MEAN?
In January, nuclear expert Siegfried Hecker warned that Seoul acquiring a bomb would encourage North Korea to construct a larger arsenal and likely lead to severe economic sanctions on South Korea.

He said that despite South Korea’s technical expertise and civilian nuclear program, building a nuclear weapons would take years and end its U.S. alliance and nuclear umbrella.

It would also endanger global non-proliferation.

“South Korea would be the first democratic country to withdraw from the NPT, dealing a blow to decades of U.S. leadership in preventing nuclear proliferation,” Hecker added. “Washington would have no choice but to condemn and counter the South’s decision to build the bomb.”

“The South can have its own nuclear arsenal—at enormous price and sacrifice—or cooperate with the Americans to remain under the nuclear umbrella with American soldiers stationed on the peninsula. It’s either/or.”

Reporting by David Brunnstrom in Washington; additional reporting by Josh Smith, Soo-hyang Choi, and Ju-min Park in Seoul; editing by Don Durfee and Michael Perry