Updated January 10, 2023
South Korea: Background and U.S. Relations
Overview
Korea, offering to meet “without preconditions,” and that
South Korea (officially the Republic of Korea, or ROK) is
“the ball is in [Pyongyang’s] court.” Since the collapse of
one of the United States’ most important strategic and
former President Donald Trump’s diplomatic outreach with
economic partners in Asia. The U.S.-ROK Mutual Defense
North Korean leader Kim Jong-un in 2019, however,
Treaty, signed in 1953 at the end of the Korean War,
Pyongyang largely has ignored U.S. and South Korean
commits the United States to help South Korea defend
outreach and has severed all overt inter-Korean
itself, particularly from North Korea (officially the
communication channels for extended periods.
Democratic People’s Republic of Korea, or DPRK).
Approximately 28,500 U.S. troops are based in the ROK.
Since the start of 2022, North Korea has test-launched more
The economic relationship is bolstered by the U.S.-South
than 60 missiles, including multiple tests of intercontinental
Korea Free Trade Agreement (KORUS FTA), implemented
ballistic missiles (ICBMs), which are capable of delivering
in 2012. In 2021, South Korea was the United States’
nuclear warheads. Satellite imagery publicized in 2022
seventh-largest trading partner (goods and services trade
appeared to indicate repairs and enhancements at North
combined), and the United States was South Korea’s
Korea’s nuclear weapons test site, raising concerns that it
second-largest trading partner, behind the People’s
will conduct its seventh nuclear weapons test, which would
Republic of China (PRC, or China). Over the past decade,
be the first since September 2017. In 2022, Kim pledged to
congressional interest in U.S.-ROK relations often has
“exponentially increase” North Korea’s nuclear weapons
focused on U.S.-ROK cooperation over North Korea and
stockpile, said he will “never” denuclearize, and
more recently Indo-Pacific policies, the U.S.-ROK alliance,
promulgated a new law expanding the conditions under
and U.S.-South Korea trade and investment flows.
which North Korea would use nuclear weapons to include
non-nuclear attacks and situations that threaten the regime’s
South Korean President Yoon Suk-yeol, in office since May
survival. Pyongyang continues to evade sanctions and
2022, is seeking to transform South Korea into a “global
conduct illicit activities to raise funds. Inter-Korean
pivotal state” by raising its profile beyond the Korean
tensions have increased since the summer of 2022. In
Peninsula, working more expansively with fellow
December 2022, for instance, the DPRK flew drones across
democracies, and becoming a more active partner in the
the demilitarized zone (DMZ) separating the two Koreas.
United States’ Indo-Pacific strategy. Yoon issued South
Korea’s first-ever Indo-Pacific strategy in December 2022.
Whereas the previous ROK government emphasized
President Joseph Biden and Yoon have capitalized on
diplomacy with North Korea, Yoon and Biden have
greater U.S.-ROK strategic alignment by forging closer
emphasized deterrence. They have reactivated high-level
cooperation on North Korea policy through military
consultations on extended deterrence under the U.S. nuclear
exercises and expanding trilateral cooperation with Japan.
umbrella and expanded the scope and scale of combined
They also have made efforts to integrate South Korean
military exercises (including with Japan), which President
companies with U.S. efforts to promote technological
Trump and Yoon’s predecessor, Moon Jae-in, had curtailed
development and supply chain resiliency. South Korea is
since 2018. The United States has increased deployments of
one of 14 negotiating partners in the U.S.-led Indo-Pacific
strategic assets such as stealth fighter jets, introduced new
Economic Framework for Prosperity (IPEF) initiative, a
unilateral sanctions designations, and proposed new DPRK
proposed new trade and economic arrangement. Despite the
sanctions measures in the United Nations. (China and
growing alignment, South Korea’s approach to China is less
Russia vetoed the attempt.) Alongside these steps, the two
confrontational than the United States’, and U.S.-ROK
allies have offered Pyongyang unconditional humanitarian
economic friction has increased due to South Korean
assistance, and Yoon has pledged to provide large-scale
complaints about the electronic vehicle (EV) provisions in
economic assistance if North Korea “embarks on a genuine
the 2022 Inflation Reduction Act (IRA, P.L. 117-169).
and substantive process for denuclearization.”
North Korea Policy Coordination
U.S.-South Korea Security Issues
Historically, North Korea has been the dominant strategic
The Biden Administration has worked to repair the alliance,
concern in the U.S.-South Korea relationship. The Biden
which had been strained under Trump, prompting the 115th
Administration in 2021 stated it will pursue a “calibrated,
and 116th Congresses to impose conditions (via the
practical approach that is open to and will explore
FY2019, FY2020, and FY2021 National Defense
diplomacy with North Korea” to eventually achieve the
Authorization Acts) on Trump’s power to withdraw U.S.
“complete denuclearization of the Korean Peninsula,” even
troops from South Korea. In February 2021, the Biden
as U.S. and international sanctions remain in place. The
Administration concluded a cost-sharing negotiation with
Administration appears to envision offering some sanctions
South Korea that boosted South Korea’s contribution to
relief in exchange for steps toward denuclearization.
alliance costs by 13.9%. The ROK traditionally has paid for
Administration officials say they have reached out to North
about 50% (over $800 million annually) of the total non-
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link to page 2
South Korea: Background and U.S. Relations
personnel costs of the U.S. military presence, according to
multiple ROK-Japan-US summits, expanded trilateral
congressional testimony by U.S. military officials.
military exercises, and an agreement to share data on DPRK
missiles in real time. It remains unclear, however, how the
Washington and Seoul have been adapting the alliance to
ROK and Japan will resolve their thorniest historical
recognize South Korea’s increased capabilities and desire
frictions in order to deepen trust.
for greater autonomy. For over a decade, they have been
preparing to transfer wartime operational control (OPCON)
U.S.-South Korea Economic Relations
to a binational command led by an ROK general with a
U.S. goods and services exports to South Korea totaled
U.S. deputy. Under the existing arrangement, South Korean
$86.1 billion in 2021, and imports totaled $108.4 billion.
soldiers would be under a binational command led by a
Autos and parts accounted for one-quarter of U.S. imports
U.S. general in the event of war. The two sides have
($27.1 billion). In 2021, the stock of South Korean FDI in
established conditions and benchmarks to demonstrate that
the United States was $72.5 billion, up 14.9% from 2020,
the ROK can assume wartime OPCON, including improved
and U.S. FDI to South Korea was $38.1 billion. Over
ROK capabilities to lead combined forces and counter the
80,000 workers in the United States were employed by
DPRK nuclear and missile threat, and a security
South Korean multinational firms in 2020. In 2022, South
environment on the Peninsula conducive to a transfer.
Korean companies announced pledges of $25 billion in new
Additionally, U.S. forces in the ROK have consolidated
U.S. investment in key industries including EVs,
their presence, in part to return land to South Korea. South
semiconductors, and biotechnology.
Korea has paid $9.7 billion—about 94% of total costs—to
The KORUS FTA has been the centerpiece of U.S.-South
construct new facilities such as Camp Humphreys, the
Korea trade and investment relations since its entry into
largest overseas U.S. base. Another example of alliance
force in 2012. Most U.S. business groups support the
adaptation is a May 2021 decision to terminate their
agreement, highlighting market access improvements in
bilateral Missile Guidelines agreement, originally signed in
South Korea and a more robust mechanism for dispute
1979, which limited the range of South Korean ballistic
resolution. The Trump Administration negotiated limited
missiles to 800 kilometers (497 miles).
modifications to the KORUS FTA, which took effect in
Reaction to Russia’s War in Ukraine
2019, to address some implementation concerns. The two
After Russia’s February 2022 invasion of Ukraine, South
countries continue to engage on outstanding issues. South
Korea imposed sanctions against Russia and offered $100
Korea’s participation in the IPEF initiative may provide an
million in humanitarian aid and nonlethal equipment to
opportunity to further enhance economic ties, including on
Ukraine. Poland reportedly has signed contracts to purchase
digital trade issues, a priority area for both countries.
over $3 billion in South Korean arms to replace equipment
South Korea has raised concerns over the IRA’s assembly
sent to assist Ukraine. Yoon also joined a 2022 NATO
and sourcing requirements, which South Korean EVs are
summit in Madrid, a first for an ROK leader.
unable to meet over the next few years. In December 2022,
South Korea’s Regional Relations
the Biden Administration reaffirmed its commitment to
continue bilateral discussions regarding the issue. Trump-
China is South Korea’s largest trading partner and second-
era import restrictions on South Korean products, including
largest destination for foreign direct investment (FDI). In
steel, aluminum, washing machines, and solar products,
the past, Beijing has imposed retaliatory economic
measures on South Korean companies for Seoul’s policy
remain in effect.
choices. Also, PRC support or opposition could be decisive
South Korean Politics
in shaping the outcome of South Korea’s DPRK policies.
Yoon, who won the 2022 election by a margin of less than
Opinion polls show strong negative South Korean attitudes
1% of the vote, is contending with a National Assembly
toward China. Even as Yoon often has shown caution in his
firmly controlled by the opposition Minjoo Party. (See
relations with China, he has pushed back against China’s
Figure 1.) Divided government, and Yoon’s low public
efforts to curtail the ROK’s expansion of its military
approval (in the 30% range) is complicating his ability to
posture and its security cooperation with the United States
secure major achievements in areas that require new
and Japan. He also has indicated interest in participating in
legislation, such as in domestic policy.
the vaccine, climate change, and emerging technology
working groups established by the Quadrilateral Security
Figure 1. South Korea’s National Assembly
Dialogue (or “Quad”), a group comprising 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. Since 2018, a series
of actions and retaliatory countermeasures by both

governments involving trade, security, and history-related
Source: National Assembly website, accessed June 4, 2022.
controversies caused South Korea-Japan relations to
plummet, eroding U.S.-ROK-Japan policy coordination.
Mark E. Manyin, Specialist in Asian Affairs
With encouragement from the Biden Administration, Tokyo
Emma Chanlett-Avery, Specialist in Asian Affairs
and Seoul took steps to reverse this trend in 2022, including
Liana Wong, Analyst in International Trade and Finance
a bilateral heads-of-state meeting (the first since 2019),
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South Korea: Background and U.S. Relations

IF10165


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https://crsreports.congress.gov | IF10165 · VERSION 34 · UPDATED

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