North Korean leader Kim Jong-un, second from left, and North Korean officials attend a launching ceremony for a tactical nuclear attack submarine, Sept. 8, 2023. AP-Newsis

South Korea has long faced the threat of its nuclear-armed northern neighbor, a risk that continues to grow as North Korean leader Kim Jong-un vows to expand his country's nuclear weapons program.

But what if both Koreas possessed nuclear weapons? Would it strengthen Seoul's deterrence and create a balance of power — or would it turn the Korean Peninsula into one of the world's most dangerous flashpoints?

The debate over whether South Korea should abandon its long-standing nuclear-free policy and develop its own nuclear weapons has resurfaced after the U.S. Department of Energy recently designated Seoul as a "sensitive country." This move placed South Korea on a list that primarily consists of U.S. adversaries such as China, Russia, Pakistan, North Korea and Iran.

Speculation that this designation may signal growing U.S. concerns over increasing voices in South Korea advocating for nuclear armament has sparked further debates among scholars and politicians.

At the heart of the debate over South Korea acquiring its own nuclear weapons are three main considerations: whether it has a clear justification for developing them, the technical and diplomatic feasibility, and whether the export-reliant nation could withstand sanctions if the international community opposes it.

"Simply put, South Korea is in the worst position to develop its own nuclear weapons," Jun Bong-geun, a nuclear expert and head of the Korea Nuclear Policy Society, told The Korea Times.

"If you look at cases like Pakistan or North Korea, any country pursuing nuclear weapons must be prepared for severe international sanctions, even at the risk of being labeled a rogue state. Do we have a national consensus on this? Is our leadership strong enough to push it through? " he said. "The answer is no."

One key question is whether the United States, which has long upheld nuclear nonproliferation, would permit South Korea to develop nuclear weapons. Some argue that President Donald Trump, a skeptic of alliances who wants to reduce the financial burden of protecting U.S. allies, might be open to the idea, as it could lessen Washington's responsibilities on the Korean Peninsula.

U.S. President Donald Trump signs an executive order imposing a 25 percent tariff on all cars that are shipped into the United States during an address from the Oval Office at the White House in Washington, Wednesday (local time). UPI-Yonhap

However, Jun believes this is unlikely.

"I don't think Washington, even under Trump, will abandon its nonproliferation policy, which remains a cornerstone of its foreign policy," he said, pointing out that U.S. Secretary of State Marco Rubio recently publicly opposed Ukraine going nuclear — a country which is in a more dire situation than South Korea.

Beyond political considerations, some also question whether South Korea actually has the capability to develop enrichment or reprocessing facilities, which are essential for nuclear weapons development.

"Without any facilities, it would take at least three years to build the necessary infrastructure, even in an optimistic scenario. And that's assuming our nation isn't hit with sanctions that would block us from obtaining necessary materials," Jun said.

Nevertheless, discussions about South Korea developing nuclear weapons are unlikely to fade anytime soon, especially amid growing skepticism over the reliability of U.S. extended deterrence.

Public support for nuclear armament, which has reached 60 to 70 percent in recent surveys, appears to stem from the belief that South Korea must take a bold step for its own defense against the North's expanding nuclear threats.

Cheong Seong-chang, director of the Center for Korean Peninsula Strategy at the Sejong Institute, is a vocal advocate for South Korea going nuclear. He leads a group of local researchers pushing for nuclear weapons development and authored a book in 2023 supporting this stance.

"The topic, once tabooed among scholars, gained significant attention since 2022 when Russia invaded Ukraine, and Kim Jong-un drastically stepped up his nuclear ambitions," Cheong said.

U.S. Forces Korea troops participate in a joint exercise with Korean troops in Paju, Gyeonggi Province, March 19, during the Korea-U.S. joint Freedom Shield exercise. Yonhap

He explained that if South Korea were to possess its own nuclear weapons, its security and inter-Korean relations would no longer be significantly affected by changes in U.S. policies. At times, Seoul has been left frustrated when the U.S. used its security guarantees as bargaining chips — such as when Trump threatened to withdraw U.S. troops from Korea unless Seoul shouldered more defense costs.

"Imagine if the U.S. decides to withdraw U.S. Forces Korea (USFK). In that scenario, even those who currently oppose nuclear armament would seriously consider it. But by then, it would be too late for us to begin discussions," Cheong said.

"It is a long-term agenda that cannot be accomplished in a short period. That's why we need to begin a thorough review. At the same time, we must engage in diplomatic efforts to persuade neighboring nations, such as China and Japan, to accept our position," he added.

He also viewed that Trump could be open to South Korea acquiring nuclear potential.

"We could negotiate revisions to the South Korea-U.S. nuclear energy agreement and use it as leverage if Trump demands higher defense cost-sharing. That way, we could secure nuclear potential and shorten the lead time for developing actual nuclear weapons," he said. "From a U.S. strategic perspective, a nuclear-armed South Korea could help deter China."

Supporters of acquiring nuclear weapons also point to similar discussions emerging in European nations, such as Germany and Poland.

"In a world where the U.S. no longer wants to act as the global police, each country needs its own means of ensuring security," Cheong said.