Joseph Yun, then-U.S. special representative for North Korea policy, answers questions from reporters following a meeting with Japanese and South Korean chief nuclear negotiators in Tokyo, in this April 25, 2017 photo. AFP-Yonhap

Joseph Yun, former U.S. special representative for North Korea policy, has been appointed as the charge d'affaires to South Korea following the departure of U.S. Ambassador Philip Goldberg, according to diplomatic sources on Tuesday.

The appointment of a new charge d'affaires to South Korea during an envoy vacancy marks a departure from previous U.S. practices, where the deputy chief of mission would typically take on the role of acting ambassador.

This appears to signal Washington's intention to maintain stability in the bilateral alliance during a sensitive period. South Korea is navigating political turbulence following the impeachment of President Yoon Suk Yeol, while Washington faces policy uncertainties with President-elect Donald Trump set to take office on Jan. 20.

Yun is expected to arrive in Seoul as early as this week. Unlike a formal ambassador, a charge d'affaires does not require an agrément process or formal credentials.

The retired Korean American diplomat will be tasked with fine-tuning South Korea-U.S. relations until Trump appoints a new ambassador.

The 70-year-old has previously served at the U.S. Embassy in Seoul, with other overseas assignments in Thailand, Indonesia, Hong Kong and Malaysia.

After serving as the U.S. ambassador to Malaysia from 2013 to 2016, Yun was appointed the special representative for North Korea policy in October 2016 under the Obama administration. In this role, he spearheaded diplomatic efforts to address Pyongyang's nuclear ambitions and facilitated the release of detained Americans in North Korea.

Kim Hong-kyun, center, then-special representative for Korean Peninsula Peace and Security Affairs at the Ministry of Foreign Affairs, speaks during a joint press conference with then-U.S. Special Representative for North Korea Policy Joseph Yun, left, and then-Japan's Asian and Oceanian Affairs Bureau Director-General Kenji Kanasugi following their meeting in Seoul, in this Dec. 13, 2016 photo. Yonhap

In June 2017, he traveled to Pyongyang to bring back Otto Warmbier, a U.S. college student who had fallen into a coma while detained in North Korea. Yun retired from government service in March 2018.

His return to South Korea is expected to help minimize the potential gap created by the vacancy in the U.S. ambassador role, a position that has often remained unfilled for extended periods during leadership transitions.

For instance, there was a nearly 18-month gap between former U.S. envoy Mark Lippert's departure in January 2017 and his successor Harry Harris assuming the role in June 2018. Goldberg took office in July 2022, about 18 months after President Joe Biden's inauguration in January 2021.

It remains uncertain when a new ambassador will be nominated and confirmed under the Trump administration. Some reports suggest that former Republican Rep. Michelle Park Steel, a Korean American politician who represented California's 45th district, is being considered for the role.

U.S. Ambassador to South Korea Philip Goldberg waves after an impromptu press conference at Incheon International Airport, Tuesday, as he returns home following the end of his two-and-half-year term in Seoul. Yonhap

Meanwhile, earlier in the day, Goldberg concluded his two-and-a-half-year tenure in South Korea, his final mission after 36 years of diplomatic service.

During his tenure, bilateral relations saw significant developments. Yoon made a state visit to Washington in April 2023, during which the two leaders signed the Washington Declaration that upgraded their security alliance to a nuclear-based one.

However, as Goldberg's term came to an end, he faced significant challenges in maintaining relations due to political upheavals in South Korea since Yoon's short-lived martial law on Dec. 3.

Speaking to reporters at the airport before his departure, Goldberg reflected on Korea's resilience amid its current crises, including the declaration of martial law and the tragic Jeju Air plane crash in Muan on Dec. 29.

"I know these are very difficult moments for Korea, but I also know that you'll get through them and that the Korean people will get through them," he told reporters."You have so many things going for you, a great democracy that I think will continue to function and work, and we'll work out these problems."

Commenting on the potential direction of U.S. policies under Trump's administration, Goldberg said, "Democracy, human rights, all of those issues will continue to be part of the expression of the American people. I can't speak to what policies necessarily President Trump and his administration will follow, but I know the American people believe in those principles."