Security and Foreign Policy

Japan and South Korea’s Souring Relations: In it for the Long Haul?

Japan and South Korea's tensions are running high once again following an ongoing maritime dispute, putting at risk any longterm detente between the countries. Nate Kerkhoff provides an analysis of the longstanding grievances between the two nations and their impact on future relations.

BY: NATE KERKHOFF

Japan-South Korea relations have not rang in the New Year on a high note. The two countries are currently engaged in a maritime spat that began with an incident from last December when a Japanese patrol aircraft accused a South Korean destroyer of “painting” it with its firing radar. South Korea denied the accusation and blamed the aircraft for making threatening maneuvers during a maritime rescue. In January, Seoul accused Japanese aircrafts of more aggressive maneuvers towards South Korean navy vessels, a charge Tokyo denies. 

This is coming on the heels of the October 2018 decision by a South Korean high court that allowed representatives of South Koreans that were forced into labor in Japanese factories during WWII to proceed in their demands of compensation from Sumitomo Steel and Nippon Steel. The court even threatened to confiscate the two corporations’ Korean-held assets. There are currently more than a dozen cases similar to this one working their way through the South Korean legal system. 

Although the two cases are technically unrelated, any disagreement between the two is associated with Japanese past militarism and colonization of the Korean Peninsula from 1910-1945. 

The current controversy has escalated to the highest levels of military and government. In recent years, relations between the two major trading partners, liberal democracies, and American allies, have experienced ebbs and flows. However, this time, relations may remain in a prolonged ebbed state. 

This outlook stems from three principal factors.

Domestic Politics

The leaders of both countries need to appeal to their respective home audiences. President Moon of South Korea is facing a bleak economic future, while Prime Minister Abe of Japan needs to shore up support for his agenda with the upcoming Diet elections in July. 

On historical issues, Tokyo remains steadfast in the position that it has made repeated conciliation gestures since the end of WWII- most recently in 2015, during the previous Park administration, when it signed an agreement with Seoul intending to put the highly controversial Comfort Women issue to permanent political rest. Fast forward to 2018, President Moon said the issue is not fully resolved and threatened to disband the fund created to distribute compensation for the victims. As for the forced labor issue, Japan claims that the massive sums provided to South Korea when the two countries normalized diplomatic relations in 1965 settled claims for financial restitution. 

Now, with the threat to seize South Korean-held assets, more court cases on the docket, and potential reopening of the Comfort Women issue, admitting fault in the military dispute would be seen in Japan as political capitulation to Seoul. 

South Korea’s stance has been that Japan has not shown sincere efforts to officially renounce its aggressive past. Both liberal and conservative administrations over the years have taken this approach, sometimes due more to domestic reasons than action from Tokyo. The Moon administration indicated that the treaty that normalized diplomatic ties does not prevent South Korean citizens from civil action against their former aggressor, potentially exposing more Japanese companies operating in South Korea to litigation.  

A confrontational posture with Tokyo has traditionally been a politically useful tool in South Korea. Now Tokyo is worried that it can be employed to bring together not just South Koreans, but North Koreans as well.

Diplomacy with North Korea

The current diplomatic detente with North Korea has further eroded common ground between South Korea and Japan. The current South Korean administration has all but staked its legacy on changing the fundamental nature of relations with North Korea, already holding three inter-Korean summits and working to irreversibly lower chances of conflicts on the peninsula. 

Japan has also been hoping for a meeting with Kim Jong Un. But now that leaders from the United States, China, and South Korea have all met with the North Korean leader, Tokyo has nothing it can offer, effectively being shut out of diplomacy.

Though Seoul and Tokyo signed an intelligence-sharing pact in 2016, rapprochement with Pyongyang has skewed their respective security planes. 

Each nation’s most recent official defensive position regarding North Korea illustrates this point. South Korea’s 2018 defensive white paper recognizes the military threat from North Korea, but has removed the country as its official enemy. Japan, on the other hand, unambiguously regards North Korea as its “most pressing” security threat. 

Since South Korea has changed its official defense posture, it will not feel compelled to share any substantial military intelligence with its counterparts in Japan, and the two countries have cancelled upcoming military exchanges.

As long as diplomacy with Pyongyang is moving forward, Seoul has less incentive to accommodate Tokyo, especially when it regards Japan as a reckless actor. 

Japan Rearming

While all these events have been taking place, Japan has been methodically rebuilding its military. In December, cabinet ministers approved a five-year plan that sees defense spending hit record highs, including offensive-capable aircraft carriers and more high-advanced missile defense systems.

Besides buying military equipment from the United States to placate the American president, Prime Minister Abe has long wanted to strengthen Japan’s military by amending the restraints place by the post-WWII constitution. With an ambitious China, the unabated missile threat from North Korea, and now a potentially unpredictable United States, Abe may get his wish.

This is of course concerning to the nations who suffered at the hands of the Japanese war machine in the 20th Century. China and South Korea have looked on warily at Japanese military ambitions, and Tokyo’s adventurism with South Korean vessels during a time of rearming is not assuring.

China and South Korea have also been big spenders on the military front, but it is very likely they may use Japan’s military spending combined with historical grievances to justify further buildup, potentially sparking a regional arms race.  

Headache for Washington

Conflicts between South Korea and Japan have caused headaches for Washington as American planners see regional relations from a geostrategic perspective. In the newly passed Asian Reassurance Initiative Act, a principle component calls for the United States to strengthen trilateral ties with Japan and South Korea. This will be increasingly difficult as Seoul and Tokyo not only do not agree on mutual security challenges, but may also come to view each other as threats.   

The United States has learned to tread lightly around sensitive historical issues between the two. So far, the US has not asserted itself diplomatically in the current scuffle. The difficult truth for Washington is it may have few options but to serve as no more than a military interlocutor ifasked.

Bumpy Road Ahead

Due to the nature of domestic politics in both nations, it is inevitable that multiple conflicts in different arenas between Japan and South Korea will overlap. But if the governments and respective publics continue to associate historical issues with current controversies, it will create a ‘whole is greater than the sum of its parts scenario’ in overall relations, making areas for cooperation more difficult to find. 

As the two Koreas are going full steam ahead with diplomacy and Japan increasing its defense capabilities, these events may mean that South Korea-Japanese relations may not improve any time soon. 

While strategists in Washington are certainly hoping for the two to resolve their differences quickly, the leaders in Pyongyang will be more than happy to fan the flames, and if it gets its way, it will be a long, slow burn.


Nate Kerkhoff has an MA in international relations and security from the Graduate School for International Studies at Yonsei University in Seoul, South Korea. He focuses on political, economic, and security aspects of Northeast Asia. He is also a Young Scholar at the Pacific Forum.

Please note that opinions expressed in this article are solely those of our contributors, not of Political Insights, which takes no institutional positions.

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