The Kim Jong-un regime won’t be deterred by a nuclear-armed South Korea, a former United States Forces Korea commander said. It would, in turn, speed up North Korea’s already-accelerated pace of nuclear buildup and the nuclear arms race in the Indo-Pacific region, where major flash points have long existed and have become more dangerous and volatile in the midst of the growing US-China rivalry.

“You don’t have to have a nuke to take out a nuke,” Walter L. Sharp, who served as the US Forces Korea commander from 2008 to 2011, said Tuesday in an interview on the sidelines of the Asan Plenum 2023 in Seoul.

Sharp believes that South Korea’s potential losses from breaking nonproliferation promises outweigh any possible gains.

A nuclear-armed South Korea would rather accelerate the nuclear proliferation of an emboldened Kim Jong-un regime, instead of deterring North Korea’s nuclear buildup.

“What’s North Korea’s reaction going to be?” Sharp said. “North Korea says, ‘Okay, we’re going to do stuff before you have a chance to really get them here.’ That type of thing.”

Seoul’s nuclear acquisition will also trigger a nuclear arms race in the Indo-Pacific region, where the security situation has already been made more fluid, intricate and perilous by arousing the desires of other countries to develop their own nuclear weapons.

“Bringing nuclear weapons here to the peninsula or South Korea developing their own nuclear weapons is very dangerous for the region,” Sharp said, raising opposition to suggestions about South Korea’s acquisition of its own nuclear weapons or the redeployment of tactical nuclear weapons on the Korean Peninsula.

“I also worry that (the) more nuclear weapons (there are), (the) more possibilities of an accident,” he said.

Nevertheless, the retired four-star Army general -- whose father participated in the 1950-53 Korean War -- said he could understand why nuclear policy debate has rapidly evolved in South Korea in the aftermath of North Korea’s passage of legislation permitting it to strike first with nuclear weapons and explicit threats to strike targets in South Korean territory with tactical nuclear weapons.

In particular, more than half of the South Korean population lives in the Seoul metropolitan area, which is located close to the heavily fortified Inter-Korean border and therefore would face an existential threat from North Korea if it were to strike.

A poll released by the Asan Institute for Policy Studies in April showed that 54.7 percent of South Koreans supported the country’s nuclear armament even though the option could bring about economic sanctions on the country.

To counter North Korean threats in an effective and efficient manner, Sharp underscored that efforts should be made at the bilateral and multilateral levels to enhance deterrence and response capabilities.

The Yoon Suk Yeol government has sought to improve the credibility and viability of the US strategy of extended deterrence, which is the US’ commitment to deter or respond to coercion and external attacks on US allies and partners with the full range of its military capabilities, including nuclear weaponry.

“What more both countries could offer is more planning together, more exercising together,” Sharp answered when asked what the US could do to strengthen extended deterrence and clear up South Korean doubts over the credibility of the US commitment to defense. He cited tabletop exercises designed to discuss ways to develop a joint strategy and response to North Korea’s potential use of nuclear weapons, as one good example.

Sharp underlined that South Korean and US forces are in need of continuous exercises and joint planning in light of the rotation of enlisted military personnel and the complexity of defending South Korea, which is a densely populated small country, from North Korea on the northern part of the Korean Peninsula.

“The synchronization (of forces) is needed in order to be able to do the best that we can to save lives here. It is a very, very difficult task to be able to do that,” Sharp said.

“It is like telling football teams, ‘Well you only need to practice once or twice, and then you know where to kick the ball, and you know the rules of going in. But just go out there. I'm sure you’ll be fine.’ It’s not quite that simple.”

More importantly, Japan should be included in the discussion, consultation and planning on how to “best deter North Korea’s use of nuclear weapons from a regional perspective.”

“Any conflict here is going to be regional,” he said. “It needs to be regional. It’s much more effective if it is a regional type of deterrence and a regional type of response if necessary.”

North Korea could theoretically attack either South Korea or Japan or both with nuclear-capable missiles.

“From my perspective, the most important thing is to have a true deterrence capability and a true strike capability,” Sharp said. “What the US brings with our capability, and combined capabilities -- not only nuclear but conventional between the US, South Korea and Japan -- are what’s needed.”

There is also a chance that North Korea would seek to escalate tensions on the Korean Peninsula in event of a Taiwan-related contingency, which could lead to a two-front war in the Indo-Pacific region.

There is a chance that the coalition between China and North Korea could grow if strategic competition between the US and China intensifies.

“It could also be at the prodding of China,” he said. “China could say to North Korea: ‘Okay, we’re dealing with the US down here but we want you to also do things that will help us.’ We’re now talking about two major conflicts in a region, which is very, very, very, very difficult to manage.”

More importantly, South Korea, the US and Japan should also improve security and military cooperation to make contingency plans jointly and sketch out scenarios of how they can respond if North Korea uses nuclear weapons from a regional perspective.

The three should jointly discuss and plan what kind of capabilities they should strengthen to counter and deter North Korean threats and deal with contingencies effectively. Then they need to conduct combined exercises.

That is the way to enhance the viability of US extended deterrence by facilitating the expeditious deployment of US strategic assets, for instance.

“It’s not just exercising,” he said. “More regional planning. Putting together planning of what would be responses in these different types of scenarios looking at it from a regional perspective.”

Sharp said that the three countries should take further steps to ensure sufficient interoperability of each military’s command, control and communication system, which is similar to an airport control tower and encompass the capability to acquire, process and disseminate information.

“So focusing on command, control and communication from a trilateral regional perspective also continues to be improved and probably needs a lot more work.”

Seoul, Washington and Tokyo also have worked to share North Korean missile warning data in real time. In March, South Korean President Yoon Suk Yeol completed normalization of the military intelligence-sharing pact, which had been suspended amid trade and historical disputes between Seoul and Tokyo – during a summit meeting with his Japanese counterpart, Fumio Kishida.

South Korea, the US and Japan also agreed to stage missile defense exercises and anti-submarine exercises to deter and respond to nuclear and missile threats from North Korea at the senior-level Defense Trilateral Talks in mid-April.

The twist and turns in South Korea-Japan relations had impeded trilateral security cooperation and suspended combined military exercises. But Sharp does believe that the South Korean government and people have started to understand the significance of trilateral coordination better.

“Where it is now and where it’s growing is probably stronger than it’s ever been before from a military perspective. So hopefully, that’s really hard to turn around,” Sharp said. “I am optimistic that from a military cooperation perspective, it will continue to grow.”

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Walter L. Sharp is a retired United States Army four-star general, who last served as the commander of US Forces Korea, the South Korea-US Combined Forces Command and United Nations Command from 2008 to 2011.

Gen. Sharp also commanded troops in Operations Desert Shield and Desert Storm, Operation Uphold Democracy in Haiti and the Multinational Division (North) of the NATO-led Stabilization Force in Bosnia. Gen. Sharp had four assignments at the Pentagon on the Joint Staff.

Gen. Sharp was born in Morgantown, West Virginia, while his father was fighting in the Korean War. He graduated from West Point in 1974 and has a master's degree in operations research and system analysis from Rensselaer Polytechnic Institute.