National security adviser Kim Sung-han (Yonhap)

Ahead of the upcoming South Korea-US summit, rumors are circulating that President Yoon Suk Yeol's chief security adviser may be replaced.

The speculation comes in the wake of resignations of the secretaries of protocol and diplomacy, Kim Il-bum and Lee Moon-hee, respectively, whose sudden replacement has raised eyebrows.

Lee had been preparing for President Yoon's state visit to the United States scheduled for the end of April, as well as his attendance at the G-7 summit in Hiroshima, Japan in May. Just before a summit was held between South Korea and Japan on March 12, Kim, who is responsible for the president's protocol, also resigned, citing fatigue.

Despite the presidential office stating that the resignations of the two secretaries were due to personal reasons, it is uncommon for key working-level staff to resign one after another, particularly at a critical time when the president's trips to Japan and the US are pending.

According to several news media outlets, a mistake in protocol may have occurred during the preparatory process for a diplomatic event related to the Korea-US summit. The reports suggest the mistake may have played a role in the resignations of the two secretaries, although this has not been confirmed by official sources.

According to reports, US first lady Jill Biden, who has an interest in Korean culture, suggested a joint performance by K-pop girl group Blackpink and American pop star Lady Gaga for a state dinner during the Korea-US summit. However, it appears the proposal was not properly communicated to President Yoon, and as a result, the US government reportedly demanded a response from the South Korean government on several occasions due to a lack of feedback from the presidential office.

Some media outlets have also linked the situation to the replacement of the national security adviser, Kim Sung-han, who has significant influence on the president's foreign and security policy decisions.

Citing sources from the presidential office, Dong-a Ilbo reported on Tuesday that Yoon has felt the need to reform the diplomatic and security lines due to certain events, including the process of coordinating the schedule for his visit to the US. The replacement of Kim is being reviewed in this context, according to the report citing the source.

The absence of Kim Sung-han from a scheduled lecture at a "sustainable peace" discussion session held at the Ministry of Foreign Affairs has fueled speculation regarding his potential replacement. However, the presidential office denied the rumor, explaining that Kim's absence was to attend a Cabinet meeting presided over by the president.