South Korean President Yoon Suk Yeol arrived in Washington this week looking for security assurances from US President Joe Biden in light of growing threats posed by North Korea.

Speaking to the press at the White House on Wednesday after a meeting with his South Korean counterpart, Biden said, "A nuclear attack by North Korea against the United States, its allies or partners is unacceptable and will result in the end of whatever regime were to take such an action."

The US position was detailed in a joint statement on extended deterrence, titled the Washington Declaration, which also announced plans to set up a Nuclear Consultative Group designed to enhance security ties.

"It's about strengthening deterrence and response to the DPRK's (Democratic People's Republic of Korea) escalatory behavior," Biden added.

The two leaders also discussed enhanced joint military training and measures to better integrate South Korean capabilities into a joint strategic deterrence effort against the North.

Biden promises 'port visits of nuclear submarines'

Political analysts point out that the US leader's comments are in line with previous presidents' positions dating back to the Bill Clinton administration, which began in 1993.

Kim Sang-woo, a former politician with the left-leaning Congress for New Politics and now a member of the board of the Kim Dae-Jung Peace Foundation, says that, "From a South Korean perspective, the specifics of the response from the US and how it would defend South Korea against a possible North Korean nuclear attack will have been welcomed by Yoon."

"That statement is designed to make both the South Korean people and government feel more secure and reduce calls here for the South to develop its own nuclear weapons to counter the North's threats," he told DW. "The US wants Seoul to stick to the Nuclear Non-Proliferation Treaty and not go nuclear and these sorts of promises help that."

Biden also indicated that he would not advocate the return of US tactical nuclear weapons to the South.

"What the declaration means is that we are going to make every effort to consult with our allies when it's appropriate," he said. "The bottom line here is even closer cooperation, closer consultation, and we are not going to be stationing nuclear weapons on the peninsula."

A key element of the renewed US expression of support for Seoul is the promise to have US nuclear submarines make port calls in South Korea, something that has not taken place for over 40 years.

Daniel Pinkston, a professor of international relations at the Seoul campus of Troy University, told DW that security agreements between the two nations need to be broader than in the past as the challenges posed by cyber and space warfare increase.

"Fundamentally, though, South Korea wants more visible strategic assets and the US is willing to provide that… which makes much of the summit in Washington symbolic and an exercise in signaling," he said. "But that signaling is aimed directly at North Korea."

Concerns over hurting business, agitating China

The second priority of both leaders has been in the area of trade and economic cooperation, with Seoul unhappy with the terms of the US Inflation Reduction Act (IRA), which excludes South Korean companies from tax credits for the production of electric vehicles for the US market. 

Korean firms are also feeling US pressure on trading with China, even though China is a huge and lucrative neighboring market. 

"Both the US and Korea have learned as a result of the coronavirus crisis of the importance and vulnerabilities of global supply chains and the degree to which much of the world relies on Chinese inputs and components," Pinkston said. "And there is the understanding now of the national security element to this trade, with Biden's administration calling for re-sourcing things away from our adversaries and rival nations, including South Korea." 

Given the importance of the Chinese market, that is likely to prove difficult for South Korean firms to achieve quickly and smoothly, he added, especially if Beijing once again takes umbrage at Seoul shifting to become even more closely aligned with the US, Europe and Japan.

Yoon signals possible military aid to Ukraine

The two leaders will also have discussed the ongoing conflict in Ukraine. Both NATO and the Biden administration have pushed South Korea to provide Ukraine with munitions. South Korea's Foreign Trade Act, however, bars selling weapons to countries at war.

Seoul has provided Kyiv with $100 million (€90.5 million) in humanitarian aid since the war began in February 2022 and pledged $130 million in March to further support Ukraine's humanitarian and infrastructure needs.

Ahead of his state visit to the US, Yoon said South Korea might extend its support for Ukraine beyond humanitarian and economic aid if it comes under a large-scale civilian attack. The comment signaled a shift in his stance against arming Ukraine for the first time.

Yoon said his administration has been assessing how to help defend and rebuild Ukraine, just as South Korea received international aid during the 1950-53 Korean War.

The comment drew criticism from Moscow, but Kim from the Kim Dae-jung Peace Foundation said the feeling in South Korean society is that it was the appropriate position to take, and that the government has the support to take a firmer line against Russia. 

Edited by: Sou-Jie van Brunnersum