Updated April 19, 2023
South Korea: Background and U.S. Relations
Overview
(including with Japan), which President Donald Trump and
South Korea (officially the Republic of Korea, or ROK) is
Yoon’s predecessor had curtailed. The United States has
one of the United States’ most important strategic and
increased deployments of strategic assets—such as stealth
economic partners in Asia. The U.S.-ROK Mutual Defense
fighter jets—to South Korea, introduced new unilateral
Treaty, signed in 1953 at the end of the Korean War,
sanctions designations on North Korea, and proposed new
commits the United States to help South Korea defend
DPRK sanctions measures in the United Nations. (China
itself, particularly from North Korea (officially the
and Russia vetoed the attempt.)
Democratic People’s Republic of Korea, or DPRK).
Approximately 28,500 U.S. troops are based in the ROK.
Alongside these steps, the two allies have offered
The economic relationship is bolstered by the U.S.-South
Pyongyang unconditional humanitarian assistance, and
Korea Free Trade Agreement (KORUS FTA), implemented
Yoon has pledged to provide large-scale economic
in 2012. In 2022, South Korea was the United States’
assistance if North Korea “embarks on a genuine and
seventh-largest trading partner (goods and services trade
substantive process for denuclearization.” Biden
combined), and the United States was South Korea’s
Administration officials say they have reached out to North
second-largest trading partner, behind the People’s
Korea, offering to meet “without preconditions.” Since the
Republic of China (PRC, or China). Over the past decade,
collapse of Trump’s meetings with North Korean leader
congressional interest in U.S.-ROK relations often has
Kim Jong-un in 2019, however, Pyongyang largely has
focused on U.S.-ROK cooperation over North Korea, Indo-
ignored U.S. and South Korean outreach. If negotiations
Pacific policies, the U.S.-ROK alliance, and U.S.-South
restart, the Administration appears to envision offering
Korea trade and investment flows.
some sanctions relief in exchange for steps toward
denuclearization.
South Korean President Yoon Suk-yeol, in office since May
2022, is seeking to transform South Korea into a “global
Since the start of 2022, North Korea has test-launched more
pivotal state” by raising its profile beyond the Korean
than 60 missiles, including multiple tests of intercontinental
Peninsula and becoming a more active partner in the United
ballistic missiles (ICBMs), which are capable of delivering
States’ Indo-Pacific strategy. Yoon issued South Korea’s
nuclear warheads, and has boosted relations with Russia
first-ever Indo-Pacific strategy in 2022. President Joseph
and China. Satellite imagery publicized in 2022 appeared to
Biden and Yoon have capitalized on greater U.S.-ROK
indicate repairs and enhancements at North Korea’s nuclear
strategic alignment by forging closer cooperation on North
weapons test site, raising concerns that it will conduct its
Korea policy through military exercises and expanding
seventh nuclear weapons test, which would be the first
trilateral cooperation with Japan. They also have made
since September 2017. In 2022, Kim pledged to
efforts to integrate South Korean companies with U.S.
“exponentially increase” North Korea’s nuclear weapons
efforts to promote technological development and supply
stockpile, said he will “never” denuclearize, and
chain resiliency. South Korea is one of 14 negotiating
promulgated a new law expanding the conditions under
partners in the U.S.-led Indo-Pacific Economic Framework
which North Korea would use nuclear weapons to include
for Prosperity (IPEF) initiative, a proposed new trade and
non-nuclear attacks and situations that threaten the regime’s
economic arrangement. Despite the growing alignment,
survival. Pyongyang continues to evade sanctions and
South Korea’s approach to China is less confrontational
conduct illicit activities to raise funds.
than the United States’, and U.S.-ROK economic friction
had increased due to South Korean complaints about the
U.S.-South Korea Security Issues
electronic vehicle (EV) provisions in P.L. 117-169, known
The Biden Administration has worked to repair the alliance,
as the Inflation Reduction Act of 2022 (IRA). On April 26,
which had been strained under Trump, prompting the 115th
2023, Biden is scheduled to host Yoon Suk-yeol for a State
and 116th Congresses to impose conditions (via the National
Visit, including a state dinner, to celebrate the 70th
Defense Authorization Acts) on the President’s power to
anniversary of the U.S.-ROK alliance. Yoon has been
withdraw U.S. troops from South Korea. In 2021, the Biden
invited to address a Joint Meeting of Congress on April 27.
Administration concluded a cost-sharing negotiation with
South Korea that boosted South Korea’s contribution to
North Korea Policy Coordination
alliance costs by 13.9%. The ROK traditionally has paid for
Historically, North Korea has been the dominant strategic
about 50% (over $800 million annually) of the total non-
concern in the U.S.-ROK relationship. Whereas the
personnel costs of the U.S. military presence, according to
previous ROK government emphasized diplomacy with
congressional testimony by U.S. military officials.
North Korea, Yoon and Biden have emphasized deterrence.
Washington and Seoul have been adapting the alliance to
They have reactivated high-level consultations on extended
recognize South Korea’s increased military capabilities and
deterrence under the U.S. nuclear umbrella and expanded
desire for greater autonomy. Since 2006, they have been
the scope and scale of combined military exercises
preparing to transfer wartime operational control (OPCON)
https://crsreports.congress.gov

---

link to page 2
South Korea: Background and U.S. Relations
to a binational command led by an ROK general with a
trilateral military exercises, and an agreement to share data
U.S. deputy. Under the existing arrangement, South Korean
on DPRK missiles in real time. In March 2023, the Yoon
forces would be under a binational command led by a U.S.
government removed a major source of friction by
general in the event of war. The two sides have established
arranging for an ROK foundation to compensate South
conditions and benchmarks to demonstrate that the ROK
Koreans forced to work by Japanese companies during the
can assume wartime OPCON, including improved ROK
colonial period, instead of insisting the companies pay the
capabilities to lead combined forces and counter DPRK
victims, as the ROK Supreme Court had ruled. Although
nuclear and missile threats, and a security environment on
relations have improved, distrust over historical issues
the Peninsula conducive to a transfer.
remains a source of tension between the two U.S. allies.
U.S. forces in the ROK also have consolidated their
U.S.-South Korea Economic Relations
presence, in part to return land to South Korea. South Korea
U.S. goods and services exports to South Korea totaled
has paid $9.7 billion—about 94% of total costs—to
$95.5 billion in 2022, and imports totaled $132.0 billion.
construct new facilities such as Camp Humphreys, the
Autos and parts accounted for one-quarter of U.S. imports
largest overseas U.S. base. In 2021, the allies terminated a
($33.6 billion). In 2021, the stock of South Korean FDI in
1979 agreement that limited the range of ROK ballistic
the United States was $72.5 billion, up 14.9% from 2020,
missiles to 800 kilometers (497 miles).
and U.S. FDI to South Korea was $38.1 billion. Over
Reaction to Russia’s War in Ukraine
80,000 workers in the United States were employed by
Since Russia’s February 2022 invasion of Ukraine, South
ROK multinational firms in 2020. In 2022, ROK companies
Korea has imposed sanctions against Russia and offered
pledged $25 billion in new investment in key industries
over $200 million in humanitarian aid and nonlethal
including EVs, semiconductors, and biotechnology.
equipment to Ukraine. Yoon also joined a 2022 NATO
The KORUS FTA has been the centerpiece of U.S.-South
summit in Madrid, a first for an ROK leader. Poland has
Korea trade and investment relations since its entry into
signed contracts to purchase over $3 billion in South
force in 2012. Most U.S. business groups support the
Korean arms to replace equipment sent to assist Ukraine.
agreement, highlighting market access improvements in
According to press reports, the 2023 leak of classified U.S.
South Korea and a more robust mechanism for dispute
Defense Department documents may include intelligence
resolution. The Trump Administration negotiated limited
regarding internal South Korean government deliberations
modifications to the KORUS FTA, which took effect in
about possibly providing material assistance to Ukraine.
2019, to address some implementation concerns. South
ROK officials reportedly have said some of the documents
Korea’s participation in the IPEF initiative may provide an
were fabricated.
opportunity to further enhance economic ties, including on
South Korea’s Regional Relations
digital trade issues, a priority area for both countries.
China is South Korea’s largest trading partner and second-
South Korea had raised concerns over the IRA’s assembly
largest destination for foreign direct investment (FDI). In
and sourcing requirements, and engaged in bilateral
the past, Beijing has imposed retaliatory economic
discussions with the Biden Administration as the Treasury
measures on South Korean companies for Seoul’s foreign
Department wrote implementing rules. The Yoon
policy choices. PRC support or opposition could be
government reacted positively to the new rules published on
decisive in shaping the outcome of South Korea’s DPRK
March 31, 2023. Trump-era import restrictions on ROK
policies. Opinion polls show strong negative South Korean
steel, aluminum, solar, and other products, remain in effect.
attitudes toward China. Even as Yoon often has shown
caution in his relations with China, he has pushed back
South Korean Politics
against China’s efforts to curtail the ROK’s expansion of its
Yoon, who won the 2022 election by a margin of less than
military posture and its security cooperation with the United
1%, is contending with a National Assembly firmly
States and Japan. He also has indicated interest in
controlled by the opposition Minjoo Party (see Figure 1)
participating in the vaccine, climate change, and emerging
and with public approval ratings generally below 40%.
technology working groups established by the Quadrilateral
Security Dialogue (or “Quad”), a group comprising
Figure 1. South Korea’s National Assembly
Australia, India, Japan, and the United States that PRC
officials have criticized as being part of a U.S.-led “anti-
China alliance.”
ROK-Japan relations are perennially fraught because of
sensitive legacy issues from Japan’s colonization of the
Korean Peninsula from 1910 to 1945. In 2018 and 2019, a

series of actions and retaliatory countermeasures by both
Source: National Assembly website, accessed April 5, 2023.
governments involving trade, security, and history-related
controversies caused South Korea-Japan relations to
Mark E. Manyin, Specialist in Asian Affairs
plummet, eroding U.S.-ROK-Japan policy coordination.
Emma Chanlett-Avery, Specialist in Asian Affairs
With encouragement from the Biden Administration, Tokyo
and Seoul took steps to reverse this trend in 2022 and 2023,
Liana Wong, Analyst in International Trade and Finance
including three bilateral heads-of-state meetings (the first
IF10165
since 2019), multiple ROK-Japan-U.S. summits, expanded
https://crsreports.congress.gov

---

South Korea: Background and U.S. Relations


Disclaimer
This document was prepared by the Congressional Research Service (CRS). CRS serves as nonpartisan shared staff to
congressional committees and Members of Congress. It operates solely at the behest of and under the direction of Congress.
Information in a CRS Report should not be relied upon for purposes other than public understanding of information that has
been provided by CRS to Members of Congress in connection with CRS’s institutional role. CRS Reports, as a work of the
United States Government, are not subject to copyright protection in the United States. Any CRS Report may be
reproduced and distributed in its entirety without permission from CRS. However, as a CRS Report may include
copyrighted images or material from a third party, you may need to obtain the permission of the copyright holder if you
wish to copy or otherwise use copyrighted material.

https://crsreports.congress.gov | IF10165 · VERSION 39 · UPDATED

---