[4][5] President Park Geun-hye was impeached in March 2017, and there was a high probability that Moon Jae-in, who is more friendly to North Korea, would win the upcoming election.
The Trump administration was concerned that the incoming South Korean government would take a more passive stance towards relations with their Northern neighbor, and refrain from imposing strong sanctions on North Korea.
[6][7] Tensions on the Korean Peninsula escalated when North Korea conducted its sixth nuclear test in September 2017 after firing several ballistic missiles in April 2017.
[9][10] Relations were further strained as a result of President Moon Jae-in’s questions about intelligence sharing around the deployment of THAAD (Terminal High Altitude Area Defense ) assets in South Korean territory.
The conflict over the THAAD deployment deepened after the U.S. Department of Defense declined to provide answers to the questions posed by South Korean leaders.
When US President Donald Trump visited South Korea on November 7th, 2017, and conducted a press conference with Moon Jae-in.
However, conservative opposition parties in Sourh Korea insisted Trump's comments were typical diplomatic rhetoric, and the controversy about 'Korea passing' will continue because no formal agreements were reached.
Hong Jun-pyo, who was delegatee of Liberty Korea Party, made mention of 'Korea passing', and contended Moon Jae-in administration is excluded from North Korea-U.S. summit negotiation.
[17][18] On June 30, 2019, when 2019 Koreas–United States DMZ Summit was held, Trump didn't want Moon to join him according to John Bolton's book.
In response, Chinese Foreign Minister Wang Yi protested, saying, 'This decision is a setback for relations between the two countries.'
The legal foundation is "Agreement Between Japan and the Republic of Korea Concerning the Settlement of Problems in Regard to Property and Claims and Economic Cooperation".
[33] After the self-coup by Yoon Suk-yeol, leaders from around the world are avoiding diplomatic activities with the South Korean government.
[36] After the second impeachment motion was passed by the National Assembly on 14 December 2024, the U.S. government said that "We highly value the resilience of South Korea's democracy and the rule of law", and expressed its readiness to work with the acting president.