The U.S.-South Korea Alliance

The U.S.-South Korea Alliance

The longstanding U.S.-South Korea alliance, created as a bulwark against a communist North Korea, has expanded to include tighter trade ties and cooperation on global issues from climate change to international development.

Last updated October 13, 2011 8:00 am (EST)

Current political and economic issues succinctly explained.

This publication is now archived.


The longstanding U.S.-South Korea alliance, originally established during the Cold War as a bulwark against the communist expansion in Asia, has undergone a series of transformations in recent years. Since 1998, when political power passed for the first time from the dictatorial ruling party to the political opposition--the United Democratic Party--successive UDP governments have steered a more independent course from Washington, sometimes leading to friction. Among the many issues that bedeviled ties was disagreement over how to handle Pyongyang’s erratic behavior, a generational divide in South Korea on the alliance and the U.S. military presence that underpins it, an ascendant China, and disagreements during bilateral trade negotiations. In 2007, the countries signed a bilateral free trade accord and agreed to a rearrangement of the military command structure that gives Seoul a greater say in its own defense. They also narrowed their differences on North Korea policy. In 2007, a conservative--Lee Myung-bak of the Grand National Party--won South Korea’s presidency, and his party followed up with victories in the 2008 parliamentary elections, ending two decades of UDP dominance. Under Lee, U.S.-South Korean ties have flourished, in part due to the strong personal relationship between him and U.S. President Barack Obama, say experts.

What does the US-Korea Free Trade Agreement (KORUS FTA) mean for the alliance?

The KORUS FTA was signed in June 2007 as the last trade deal agreed on during President Bush’s "fast track" trade promotion authority. If ratified, the FTA would eliminate nearly 95 percent of all tariffs within five years. It was the biggest trade deal agreed on by the United States since the 1994 North American Free Trade Agreement. Korea is the seventh-largest goods trading partner of the United States, and the two-way goods trade amounted to roughly $88 billion in 2010. The U.S. International Trade Commission estimates that the tariff cuts in the U.S.-Korea trade agreement will increase exports of U.S. goods (PDF) by $11 billion annually.

More From Our Experts

During the negotiation process, both administrations faced opposition from strong domestic agricultural lobbies, but the breakthrough of the agreement came when the United States dropped pressure on opening Korea’s rice market and Korea agreed to resume importing American beef, which halted in 2003 due to fears over mad cow disease. However, the agreement faced significant opposition from the U.S. auto industry. The U.S.-Korea auto trade, which represents a significant portion of the trade, has been wildly imbalanced for decades, with South Korea selling far more vehicles in the U.S. market, say CFR’s Edward Alden and Scott Snyder. A revised agreement was concluded in December 2010, which, among other things, addressed the grievances of the U.S. auto sector (ForeignPolicy).

More on:

South Korea

United States

Nonproliferation, Arms Control, and Disarmament


In Washington, Congress finally approved the deal in October 2011, along with a renewal of the Trade Adjustment Assistance program, which helps U.S. workers displaced by imports. The FTA now requires ratification by the South Korean legislature.

What is the history of U.S.-South Korea relations?

When Japan lost control of Korea at the end of World War II, the United States and the Soviet Union split the peninsula into two territories pending promised national elections, which never took place. Instead, after Moscow and Washington failed to agree on a way forward, the United Nations in 1948 declared the Republic of Korea (ROK), with its capital in Seoul, as the only legitimate government on the peninsula. The Soviets rejected that assertion, and in 1950, the Democratic People’s Republic of Korea (DPRK) invaded. The United States, heading up UN forces, came to the aid of South Korea. War ensued until 1953, when a ceasefire froze the front line at roughly the thirty-eighth parallel.

The U.S. International Trade Commission estimates that the tariff cuts in the U.S.-Korea trade agreement will increase exports of U.S. goods by $11 billion annually.

In 1954, the United States and South Korea signed the ROK/U.S. Mutual Security Agreement, in which they agreed to defend each other in the event of outside aggression. In 1978, the two countries formed the Combined Forces Command (CFC), based in Seoul and with a U.S. general at the helm, to defend South Korea. "For decades, it was the threat from North Korea that was the glue that held the alliance together," says Donald P. Gregg, chairman of the Korea Society and former U.S. ambassador to South Korea. But the South, ruled largely by U.S.-backed authoritarian regimes until the 1990s, underwent a shift in attitude toward North Korea under liberal administrations from 1998 to 2007. President Lee Myung-bak’s administration once again took a tough line toward the North.

More From Our Experts

Under Lee and Obama, the two countries significantly improved their relations. "This has really been the high point" in the history of the alliance, says Snyder, attributing it in part to the "good, personal relationship" between the two presidents. South Korea’s growing capacity as a global actor on issues such as climate change, international development, and denuclearization has also expanded the agenda for bilateral cooperation, he says.

How does North Korea affect the U.S.-South Korean alliance?

Deterrence against North Korea is central to the U.S.-South Korea alliance, but the South Korean government’s approach to the North underwent a major shift in the late 1990s. In 1998, South Korean President Kim Dae-jung adopted the "sunshine policy," a variant of the "Ostpolitik" policies pursued by West Germany toward the Communist East during the Cold War. Kim’s initiative offered economic and humanitarian aid to North Korea in exchange for contacts between long-divided families and other cultural concessions. Kim’s successor, Roh Moo-hyun, continued the strategy in policy, if not in name, with the goals of thawing inter-Korean relations and persuading Pyongyang to stop its aggressive behavior.

Crisis Guide: The Korean Peninsula

More on:

South Korea

United States

Nonproliferation, Arms Control, and Disarmament


However, President Lee Myung-bak’s departure from his two predecessors--voting for the UN resolution condemning the human rights situation in North Korea, making economic aid contingent on the denuclearization progress of the North, and putting forth his "Vision 3000" (PDF) policy--prompted angry reactions from North Korea. North Korea’s state newspaper called Lee a "traitor" and a "U.S. sycophant," and Pyongyang expelled South Korean government officials stationed in the North and fired missiles off the west coast--all ahead of Seoul’s parliamentary elections in April 2008, which bolstered the standing of Lee’s party.

North Korea’s sinking of a South Korean warship in March 2010 and the shelling of Yeonpyeong Island, a South Korean territory, in November 2010 raised tensions. In response, South Korea and the United States held joint military exercises and Washington announced additional economic sanctions intended to further squeeze the Pyongyang regime. With growing fears of instability in the North as a result of regime succession, experts have urged greater cooperation between Washington and Seoul on contingency plans to address diplomatic, economic, security, and humanitarian challenges.

How does North Korea’s nuclear program affect U.S.-South Korea relations?

In 1994, North and South Korea, plus Japan and the United States, reached the so-called "Agreed Framework" Pact to end the North’s nuclear weapons research in return for economic and political concessions, as well as a Western-designed nuclear power-generating plant. The United States, Japan, and North Korea established the Korean Peninsula Energy Development Organization (KEDO) to carry out the terms of the pact, including an annual U.S. shipment of 500,000 metric tons of oil to the DPRK until the first nuclear reactor would be completed. Oil shipments were suspended in 2002 in light of reports that North Korea was enriching uranium, and KEDO ended nuclear plant construction the following year.

The rearrangement of the U.S.-South Korea military alliance has represented a hot domestic political issue in South Korea since the negotiation of command structure began.

Upon assuming office in 2001, President Bush ended diplomatic talks with North Korea, citing violations of the 1994 agreement by Pyongyang. By January 2002, relations frayed so badly that Bush declared North Korea to be part of the "Axis of Evil" in his State of the Union speech, referring to its nuclear weapons program. North Korea’s 2005 claim that it had nuclear weapons, punctuated by its July 2006 long-range missile tests, served to further exacerbate tensions and hardened the U.S. position against the DPRK. The White House demanded a continuation of the multilateral disarmament negotiations, which included South Korea, China, Japan, and Russia, and planned to intensify sanctions against North Korea if it did not return to the Six Party Talks.

South Korea made cuts in humanitarian aid to its northern neighbor following the July 2006 missile tests, but Seoul questioned Washington’s hard-line approach, fearing it might provoke an aggressive response from Pyongyang. Roh downplayed the importance of the July missile tests, saying the weapons would not make it to the United States but would go too far to be a threat to Seoul. He did not want to lose ground on advances made in inter-Korean relations, but his response to DPRK missile tests and his opposition to increased sanctions drove a wedge into the U.S.-South Korea alliance. East Asia scholar David C. Kang said in 2006 that the "United States is angry with South Korea for not going along, and South Korea is angry about the United States ignoring all the gains South Korea has made."

In February 2007, the resumption of the Six Party Talks led North Korea to agree to begin the disarmament process in exchange for fuel assistance. A set of events sent positive signs in 2007: the closure of North Korea’s main plant at Yongbyon in July, a second inter-Korean summit in October, and the opening of the first cross-border railroad in December. But Pyongyang missed its January 1, 2008, deadline to fully declare its nuclear activities, and the talks broke down again.

In 2008, President Lee hardened policy toward the North and his emphasis on complete denuclearization of North Korea has brought U.S. and Seoul’s policies closer. "It also deprives North Korea of the leverage with which it had previously exploited differences between Washington and Seoul," noted a 2010 CFR Task Force Report.

What is the role of China in U.S.-South Korean relations?

Up until 2007, when relations between the United States and South Korea suffered because of disagreement over how to handle North Korea, views in Seoul and Beijing on the issue had been in rough alliance. While both of North Korea’s neighbors were unhappy with the missile tests in 2006, neither China nor South Korea wanted to push the country toward actions that could result in a sudden flood of refugees. Instead, leaders of the two countries were proponents of humanitarian assistance to the DPRK.

As North Korea’s closest ally and largest provider of food and fuel, China plays a pivotal role in the success of U.S.-South Korean efforts to denuclearize North Korea. China opposes any U.S.-South Korean joint military exercises in the Yellow Sea and its primary interest--stability on the Korean peninsula--is often at odds with U.S. and South Korean interest in denuclearization. According to some reports, Beijing is growing increasingly perturbed (PDF) over Pyongyang’s intransigence on the nuclear issue.

Is there controversy over the presence of U.S. forces on South Korean soil?

In February 2007, U.S. Defense Secretary Robert Gates and South Korean Minister of National Defense Kim Jang-soo reaffirmed that the U.S. Force Korea (USFK), the combined U.S. air, ground, and naval forces, will transfer its wartime command authority to South Korea by 2012. But in September 2010, amid Seoul’s concerns over North Korea’s provocations, the two countries decided to delay the transition until 2015. The two have agreed on a slow drawdown in the number of U.S. troops, as well as a redeployment of American forces away from populated areas close to the northern border. The United States handed control of some military bases over to South Korea in 2004, and decreased its troop numbers from 37,000 in 2004 to 28,500 by 2008. South Korea is also included under the U.S. "nuclear umbrella," or "extended deterrence."

The rearrangement of the U.S.-South Korea military alliance has represented a hot domestic political issue in South Korea since the negotiation of command structure began. Citing concerns about Seoul’s defense preparedness, some conservative sectors in Korea insist on renegotiating the year of the transfer. The rise of South Korea’s defense budget from 2.8 percent of GDP in 2007 to 3.2 percent in 2008, and the costs of relocating U.S. troops out of the Yongsan garrison in Seoul, also faced criticism. Others were suspicious of the U.S. military presence and remembered the 2002 killings of two South Korean teenagers who were accidentally struck by a USFK armored vehicle, an incident that sparked widespread street protests.

In Washington, some members of Congress have criticized the relocation plans and called for reconsideration for the U.S. military presence in South Korea, according to a Congressional Research Service report (PDF). But some experts, such as Bruce Klinger of Heritage Foundation, argue that such changes would jeopardize hard-fought agreements designed to achieve U.S. strategic objectives and make the U.S. presence more politically sustainable in South Korea

Carin Zissis contributed to this Backgrounder.


Top Stories on CFR


CFR experts discuss President Joe Biden’s decision to increase tariffs on various Chinese imports and the implications for the U.S. economy and U.S.-China relations. 


Myanmar’s civil war between resistance groups and the ruling military junta has reached a decisive phase.


Despite China’s growing pressure, Taiwan has developed one of the world’s strongest democracies—one that will be increasingly tested in the coming years.