US-Japan alliance has always been the core axis for securing the stability of Northeast Asia for the US. The US-ROK alliance, albeit its increased importance along with the economic rise of South Korea, not as much. The discrepancy in the weight of each alliance had also been displayed historically when the US drew the Atchison line to ostracize the Korean peninsula out of its line of defense against Communism before the break of the Korean War. Now with potential talks of a peace treaty going on among the United States, South Korea, North Korea and China, the future of the US-Japan, US-ROK alliance seems to be at stake, with the latter being at higher risk.

During the Korean War, Japan was under the occupation of Allied Forces, functioning as a logistical base for the American troops fighting in the Korean Peninsula. With the war continuing against North Korean and later Chinese forces, withdrawing military bases from Japan was never in US interests. Hence, the first US-Japan security treaty was signed in 1951 to ensure the continued presence of American troops in Japan even after Japan’s restoration of sovereignty. Since Japan was banned from having regular forces due to its Pacifist Constitution, the Japanese government accepted this treaty to counter the external threats from Communist countries and to suppress the internal danger brought by domestic communists attempting to overthrow the government.

The treaty was updated in 1960 to perpetuate the American military’s status in Japan. However, the purpose of this alliance (namely, to deter the Communist menace) had to be redefined after the end of the Cold War. In 1997, the New Guidelines for US-Japan Defense Cooperation reframed the alliance as a regional public good contributing to the peace and stability of Northeast Asia. With problems remaining in Korea and Taiwan, complete withdrawal of American troops was too much of a risk both for the US and Japan.

Therefore, while a potential peace treaty between North Korea and South Korea may raise questions about the legitimacy of US troops in South Korea, the legitimacy of US forces in Japan is not likely to be harmed as much. Japan is not a logistical base for the troops only in the Korean Peninsula, but also played the same role in the Vietnam War as well as in the recent Iraq War. Yokosuka has the headquarters of the US Seventh Fleet which covers from the East of Indian Ocean to the Western Pacific Ocean as its operational area: nearly half of the Earth. It is the key strategic force that keeps the US dominance in the West Pacific against China.

Such scale of force is not likely to be transferred to the Philippines, which is one of the US allies near Japan, since the current Defense Cooperation Agreement between the US and the Philippines states that the permanent presence of American forces in the Philippines is not intended. In fact, the US once completely shut down its bases in the Philippines in the early 90s. Another US ally near Japan, Taiwan, cannot host any American base out of fear of provoking China. Some bases in Okinawa, Japan, where anti-American base movements are active, may be removed if the danger in Korea is reduced by the peace treaty, but the US is likely to maintain most of its forces in Japan to keep its superior military status in East Asia.

As the first and the only alliance treaty South Korea signed with any country, the US-ROK alliance has been perceived by the South Koreans as more than a simple alliance. The participation of the US forces to fend off communist aggression and the humanitarian aids that followed embedded an extremely positive image of the US’s presence in the peninsula. The initial purpose of the alliance was defending South Korea from any future North Korean aggression. However, as the South Korean economy, along with its military spending completely eclipsed that of North Korea, the purpose of US presence according to the alliance’s precepts became questionable. Now the alliance remains as a deterrence for war or aggression with overwhelming strength of the US-ROK alliance against North Korea.

If a peace treaty is to be signed, as Xi allegedly proposed, the role of US’s presence as a deterrent may lose its legitimacy. North Korea would not pose threat to its neighbors anymore as the treaty, if it were to be signed, would involve North Korea’s nuclear renunciation. In fact, Trump had repeatedly accused South Korea to be free riding on security although it is completely capable of tending to its own needs considering its affluence. Therefore, without the will and legitimacy of US presence, the US military may indeed retreat in such a scenario.

Whether the South Koreans want the US to withdraw its forces, however, is another question. As previously mentioned, many South Koreans, especially the elderly who have lived through the ramifications of war, still see US presence as the last threshold against communism in the peninsula. The South Korean president would have to make serious considerations on such domestic sentiments before agreeing to withdraw US forces. The US on the other hand, according to Trump, seems to be lacking willingness to continue to station its forces the peninsula. He may lose further willingness in case of a peace treaty. Then ultimately, it will be the South Koreans who may be more desperate for US presence than US itself on the premise of US reluctance if a peace treaty were to be signed.

Whether the peace treaty will be signed remains ambiguous, but considering Trump’s rhetoric since his tenure, some change in the US forces stationing in South Korea is expected regardless. On the other hand, Japan will likely to play its role as a logistic base not only for the peninsula, but for the rest of the world as a core axis of US military interests. In fact, no President of the US has ever mentioned of considering a complete withdrawal from Japan during their presidencies. The US may be confident to maintain the balance of power in East Asia without having its forces in the peninsula, but this cannot be said for the forces in Japan.

Further Reading on E-International Relations

• Opinion – Toward a Japan-South Korea Alliance Less Reliant on the US
• Normalization Negotiations between North Korea and Japan Revisited
• A Unified Korea: Good for All (Except Japan)
• Opinion – Japan-South Korea Relations: Breaking the Cycle?
• Opinion – Seventy Years of Solidarity: The ROK-US Alliance
• Opinion – Extending South Korea and Japan’s Joint Development Zone Agreement