South Korea

==== United States ====
{{Main|South Korea–United States relations}}
[[File:President Biden met with President of South Korea Yoon at the Presidential Office in Yongsan 2022.jpg|thumb|President [[Yoon Suk Yeol]] meets with [[President of the United States|U.S. President]] [[Joe Biden]] in Seoul.]]

A close relationship with the United States began directly after World War II, when the United States temporarily administered Korea for three years (mainly in the South, with the Soviet Union engaged in North Korea). Upon the onset of the Korean War in 1950, U.S. forces were sent to defend against an invasion from North Korea of the South and subsequently fought [[United States in the Korean War|as the largest contributor of UN troops]]. The United States participation was critical for preventing the [[Battle of Pusan Perimeter|near defeat of the Republic of Korea]] by northern forces, as well as fighting back for the territory gains that define the South Korean nation today.

Following the Armistice, South Korea and the U.S. agreed to a "Mutual Defense Treaty", under which an attack on either party in the [[United States Indo-Pacific Command|Pacific area]] would summon a response from both.<ref>{{cite web |title=Mutual Defense Treaty Between the United States and the Republic of Korea; October 1, 1953 |url=http://avalon.law.yale.edu/20th_century/kor001.asp |publisher=Yale Law School |access-date=18 September 2010 |archive-date=7 August 2016 |archive-url=https://web.archive.org/web/20160807165304/http://avalon.law.yale.edu/20th_century/kor001.asp |url-status=live }}</ref> In 1967, South Korea obliged the mutual defense treaty by sending a large combat troop contingent to support the United States in the [[Vietnam War]]. The two nations have strong economic, diplomatic, and military ties, although they have at times disagreed with regard to policies towards North Korea and with regard to some of South Korea's industrial activities that involve usage of rocket or nuclear technology. There had also been strong anti-American sentiment during certain periods, which has largely moderated in the modern day.<ref>{{cite journal |author=Haesook Chae |year=2010 |title=South Korean Attitudes toward the ROK–U.S. Alliance: Group Analysis |journal=PS: Political Science & Politics |volume=43 |issue=3 |pages=493–501 |doi=10.1017/S1049096510000727 |s2cid=155083075}}</ref>

The two nations also share a close economic relationship, with the U.S. being South Korea's second largest trading partner, receiving $66 billion in exports in 2016.<ref name="MIT-2018" /> In 2007, a free trade agreement known as the [[South Korea – United States Free Trade Agreement|Republic of Korea-United States Free Trade Agreement]] was signed between South Korea and the United States, but its formal implementation was repeatedly delayed, pending approval by the legislative bodies of the two countries. On 12 October 2011, the U.S. Congress passed the long-stalled trade agreement with South Korea.<ref>{{cite news |author=Appelbaum, Bintamin |author2=Steinhauer, Jennifer |date=13 October 2011 |title=Congress Ends 5-Year Standoff on Trade Deals in Rare Accord |work=[[The New York Times]] |url=https://www.nytimes.com/2011/10/13/business/trade-bills-near-final-chapter.html?scp=17&sq=korea&st=cse |access-date=18 February 2017 |archive-date=12 June 2018 |archive-url=https://web.archive.org/web/20180612142051/https://www.nytimes.com/2011/10/13/business/trade-bills-near-final-chapter.html?scp=17&sq=korea&st=cse |url-status=live }}</ref> It went into effect on 15 March 2012.<ref>{{cite news |date=9 June 2012 |title=New Opportunities for U.S. Exporters Under the U.S.-Korea Trade Agreement |url=http://www.ustr.gov/trade-agreements/free-trade-agreements/korus-fta |access-date=28 March 2024 |archive-date=21 November 2021 |archive-url=https://web.archive.org/web/20211121032246/https://ustr.gov/trade-agreements/free-trade-agreements/korus-fta |url-status=live }}</ref>