A photo distributed on Sept. 3 by the North Korean government shows North Korean leader Kim Jong Un, second from right, at an undisclosed location. (Korean Central News Agency/Korea News Service via Associated Press)

The heated debate in South Korea over redeploying U.S. nuclear weapons on its territory has now reached Washington. A senior delegation of South Korean lawmakers is in town making the case to the Trump administration and Congress that such a move is needed to confront North Korea’s growing nuclear capability and place more pressure on China.

“We are here to ask for redeployment of tactical nuclear warheads in South Korea,” Lee Cheol Woo, the head of the intelligence committee of South Korea’s National Assembly, told me Thursday morning.

Lee is heading a delegation of members of the Liberty Korea Party, the opposition to President Moon Jae-in’s Democratic Party. He is also the chairman of the assembly’s special committee for nuclear crisis response.

Moon told CNN yesterday that he does not agree that tactical nuclear weapons should be reintroduced to South Korea or that Seoul should develop its own nuclear weapons. He warned it could “lead to a nuclear arms race in northeast Asia.” But Lee’s delegation believes that as the North Korea nuclear crisis worsens, a push by the Trump administration or Congress could help persuade Moon’s government to change its position, as it has already done regarding the deployment of the THAAD missile defense system.

In response to continued testing of ballistic missiles and nuclear weapons by North Korea, the United States is in the process of deploying an advanced missile defense system called THAAD in South Korea. But China is not happy with the plan, saying the system could undermine its own defense systems. (Jason Aldag/The Washington Post)

“The ruling party came to power based on their opposition to the deployment of THAAD and having tactical nuclear weapons in South Korea,” Lee said. “But if there were to be additional requests from the U.S. government, then they would have to listen to the many voices that are asking for the additional deployment of nuclear warheads.”

The delegation will meet with the State Department’s special representative for North Korea policy, Joe Yun, and senior Asia-focused lawmakers including Sens. Cory Gardner (R-Colo.) and Dan Sullivan (R-Alaska).

The delegation touts rising South Korean public support for their initiative. Even before Kim Jong Un’s latest nuclear test, South Korean polls showed that 68 percent support reintroducing nuclear weapons and that 60 percent support South Korea developing nuclear weapons of its own.

The United States stationed nuclear weapons in South Korea for most of the Cold War, but they were removed by President George H.W. Bush in 1991. After South Korea’s defense minister suggested this month it’s worth reviewing the idea, Senate Armed Services Committee Chairman John McCain (R-Ariz.) said “it ought to be seriously considered.” Trump administration officials have said they are not ruling out the possibility, should the South Korean government request it.

Adding nuclear weapons to the already volatile situation on the Korean peninsula seems to run counter to the stated U.S. goal of completely denuclearizing the peninsula. But proponents of the idea lay out three key reasons it could be helpful.

First, North Korea is very close to achieving the capability to launch nuclear weapons via both intercontinental ballistic missiles and submarine-launched missiles. That changes the calculus of strategic deterrence. Putting nukes in South Korea would strengthen the ability of the United States and South Korea to retaliate, thereby bolstering that deterrence.

After the North's sixth nuclear test, South Korea is looking to lift a cap imposed in the 1970s on the country's missile payload size. (Reuters)

Separately, the Chinese government would surely oppose putting nuclear weapons back in South Korea. Beijing has been subjecting the South Korean economy to severe punishment in response to the THAAD deployment. But the threat of South Korea going nuclear could push Beijing into doing more to rein in Pyongyang.

Lastly, since North Korea is now a de-facto nuclear state, putting nukes back in South Korea could be a bargaining chip for future negotiations with Pyongyang.

But what about Moon’s warning about potential escalation? Kim Tae Woo of Konyang University, a member of Lee’s special committee, said that the benefits of the move outweigh the risks. “First of all, we want to destroy the North Korean belief that they can decouple the alliance by threatening the U.S. continent,” he said. “And also we have to destroy the Chinese belief that China can let the North Korea nuclear program go on.”

The current U.S. strategy is to cooperate with Beijing to increase pressure on North Korea to change its calculus and eventually bring it back to the table. “But do you think the current strategy is working?” Kim said.

So long as Moon is in power, prospects for putting nukes back in South Korea will remain slim. The Trump administration would be unwise to publicly break with Moon on such an important issue. Alliance unity is an important signal to Pyongyang and Beijing. But ignoring the fact that North Korea’s nuclear advancement is changing the strategic situation is also deeply unwise. The only thing worse than failing to prevent a new nuclear arms race would be losing it.