U.S. President Donald Trump took office determined to slow North Korea’s nuclear and missile programs. Since then, Pyongyang has accelerated the pace of its missile tests and has signaled its intention to flight-test an intercontinental ballistic missile (ICBM) capable of striking the continental United States. Meanwhile, Washington’s relationship with South Korea—a partnership that is essential to confronting the North’s advances—has been faltering since December, when South Korea’s former president Park Geun-hye was impeached. Over the months that followed, Trump administration officials met with Japanese and Chinese leaders. Yet South Korea lacked a head of state who could forge the kind of personal connection that other governments had developed with the U.S. president.

Real fissures have opened in the U.S.–South Korean alliance. If they are not repaired, the partnership could falter just as North Korea nears an operational nuclear capability. The June 29–30 summit between Trump and Moon Jae-in, South Korea’s new president, will offer the chance to mend the two countries’ neglected ties and develop a more effective policy toward North Korea. The outcome will help determine whether a nuclear North Korea is contained, constrained, and deterred.


Even though the Trump administration has prioritized North Korea and dispatched senior officials to Seoul, over the last few months, problems have appeared in the U.S.–South Korean alliance. South Korean officials have been frustrated by the U.S. administration’s vacillations over North Korea policy and by its attempts to renegotiate bilateral economic and security agreements. Such frustrations help explain why, on June 1, Moon pledged that South Korea “will take the lead in dealing with Korean Peninsula issues without relying on the role of foreign countries.”

The deployment of the Terminal High Altitude Area Defense (THAAD) system has been a particularly sensitive issue. Shortly before Moon’s election, Park’s administration authorized the installation of the U.S. missile defense system. China condemned the move and showed its displeasure by sanctioning South Korean businesses that operate in China. Trump exacerbated the pressure on South Korea by appearing to renege on Washington’s commitment to funding THAAD in late April. Around six weeks later, lacking consistent support from the United States and facing opposition from China and his own political base, Moon suspended the deployment of the missile batteries. Officially, the original bargain is still on: the Moon government has allowed the parts of THAAD already in place to remain intact and says that it is still open to completing the deployment. In the United States, meanwhile, National Security Adviser H. R. McMaster walked back Trump’s demand that Seoul pay for the system. Yet the drama surrounding the deployment has already turned THAAD from a source of strength into a political liability.

A child adjusts a South Korean flag as he awaits the  arrival of South Korean President Lee Myung-bak at the White House in Washington, October 2011.
A child adjusts a South Korean flag as he awaits the  arrival of South Korean President Lee Myung-bak at the White House in Washington, October 2011.
Kevin Lamarque / REUTERS

There have been other issues, too. In April, U.S. officials announced that they were sending an aircraft carrier strike group to the Sea of Japan in an attempt to turn up the pressure on the North; around a week later, it became clear that the American ships were actually heading toward the Indian Ocean, revealing what many South Korean observers saw as a counterproductive bluff.

The same month, on his first visit to Seoul, U.S. Vice President Mike Pence sought to reassure South Korean officials of Washington’s commitment to their security—but he also threatened to renegotiate the U.S.-Korea Free Trade Agreement, which has been in force for just five years. As it has with other trade agreements, the Trump administration has claimed that the deal is unfair to U.S. manufacturers. Although the deal isn’t perfect, lagging U.S. exports to South Korea are mostly the result of slow economic growth there. That is even more reason for Washington to preserve the deal and to protect Seoul from China’s economic coercion.

China will loom over Thursday’s summit. Moon and Trump have both taken cues from Beijing over issues that would normally be handled within the alliance—Moon by suspending THAAD, and Trump by repeating a Chinese propaganda line that the Korean Peninsula used to be a part of China. Indeed, when the Trump administration first began considering ways to ratchet up pressure on the regime, it chose to rely on Beijing rather than Seoul. It was not until June that the White House conceded that its reliance on China “has not worked out.” Indeed, there is scant evidence that the volume of Chinese–North Korean trade—on which the North Korean regime depends—has fallen.

It would benefit both countries to work with China when possible, but Beijing is unlikely to ever apply enough pressure to force Pyongyang to denuclearize. More probable is that China will seek to accommodate North Korea and fracture the alliance between the United States and South Korea in order to reshape the security architecture of Northeast Asia to its advantage.


It is still in the interests of South Korea and the United States to strengthen their alliance. For South Korea, it is a vital source of protection against the world’s most dangerous regime. For the United States, it is an invaluable tool for constraining North Korea and a cornerstone of regional stability.

There are plenty of unresolved issues in the bilateral relationship. But for now, both sides should pursue a more modest goal: a strong working relationship. Longer-term issues—such as the potential renegotiation of the U.S.–Korea Free Trade Agreement, the financing for U.S. forces on the peninsula, and the reestablishment of social and economic ties between the two Koreas—should be deferred until the alliance is on firmer footing. Expect the Moon team to come prepared with economic favors—for example, a commitment to import U.S. petroleum or to provide new foreign direct investment. This is a strategy that has worked for other leaders, including Japanese Prime Minister Shinzo Abe, who have sought to win over the Trump administration. As for THAAD, U.S. officials should not insist on its immediate deployment if doing so would derail the talks: the alliance is more important than the missile defense system.

A military parade in Pyongyang, October 2015.
A military parade in Pyongyang, October 2015.

The Trump and Moon administrations agree about the broad contours of North Korea policy: both favor increasing their militaries’ deterrent capabilities and support negotiating with Pyongyang under the right conditions. Now, they should work to develop a shared position on what conditions would allow for talks and what the agenda of those talks would be. The Trump administration should abandon its unrealistic insistence that Pyongyang “would have to denuclearize” for talks to begin, which would effectively prevent all negotiations. The Moon team needs to be clear that its engagement depends on Pyongyang accepting limits on its nuclear and missile programs and improving its human rights record.

An all-or-nothing push to eliminate North Korea’s nuclear and missile arsenals would be bound to fail. Instead, the allies should pursue a sequenced set of negotiations. The first step should be to formalize a moratorium on nuclear and missile tests. (North Korea may have floated the possibility recently.) As long as a moratorium holds, the allies should be prepared to offer real inducements in exchange for escalating restrictions on North Korea’s nuclear and missile programs. By developing a policy together, South Korea and the United States can forge a balanced and effective negotiating position. If either country attempts to work alone, it will strain the alliance and allow Pyongyang to advance unchecked.

Even if the allies do hold talks with Pyongyang, they shouldn’t count on them succeeding. North Korea has insisted that it is a normal nuclear power and will not discuss eliminating its arsenal. Any talks would be grueling and any agreement modest and prone to failure.

At best, South Korea would serve as the good cop, engaging North Korea and offering inducements, as the United States ramps up the military pressure on Pyongyang. But if these approaches are not coordinated carefully, they will undermine each other. Seoul’s economic engagement could conflict with Washington’s efforts to tighten sanctions, and U.S. military pressure could strike Seoul as unnecessarily inflammatory. This week’s summit should be the first step in ensuring that these strategies complement each other.

There are plenty of opportunities to strengthen alliance coordination on containing and deterring North Korea. In economic terms, doing so will require enforcing sanctions more rigorously. To restrict the North’s ability to fund its military and commit financial crimes, South Korea and the United States should take the lead in helping countries around the world to live up to their obligations under UN sanctions. As for defense, Seoul and Washington should reassess the military planning done by previous administrations; the last thing the alliance needs is for new leaders to revise joint military planning during a North Korean provocation or attack. Relatedly, Trump and Moon should prepare a common response to the disruptions that are likely to come this year—from a flight test of a North Korean ICBM to the detonation of another nuclear device—so that neither side is caught off-guard when such tests occur.

There is certainly more work for the White House to do at home. The United States still lacks an ambassador to South Korea, assistant secretaries for Asian affairs in both the Defense and State Departments, and State Department officials to manage the arms control and international security bureaus. Appointing capable officials to those positions is necessary for maintaining the alliance with South Korea and confronting its northern neighbor.

If the difficulties within the U.S.–South Korean alliance aren’t repaired, they will endanger the security and economic interests of both countries. Those stakes also demonstrate the enduring value of the alliance. With a strong first summit and continued coordination, the U.S.–South Korean partnership could help see both countries through volatile times.

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