In emphasizing during their April 2024 meeting in Washington DC that their “alliance cooperation” had reached “new heights,” US President Joe Biden and Japanese Prime Minister Fumio Kishida expressed the desire to further expand their engagement to reflect the “global nature” of the partnership. As their Joint Leaders’ Statement posited:
[Our] joint efforts are based on our shared fundamental respect for international law, including the protection and promotion of human rights and dignity, the sovereignty and territorial integrity of all states, and the prohibition on acquisition of territory by force. Our purpose as partners is to uphold and bolster the free and open international order based on the rule of law that has allowed so many nations to develop and prosper, and to ensure our Alliance is equipped to tackle the challenges of the 21st century.
The above statement highlights the joint commitment of both governments towards protecting the sovereignty and territorial integrity of all states, and the prohibition on acquiring territory by force resonates with the provisions of the Treaty of Mutual Cooperation and Security between Japan and the United States of America of 1960 (the earlier version of the Treaty was signed in 1951).
In light of the growing Chinese threat to Taiwan, one aspect of the US-Japan relationship that deserves further attention is this: What does a rise in cross-Strait tensions imply for the US-Japan alliance, and how do concerns surrounding Taiwan factor into alliance dynamics?
Mentions of Taiwan by Japanese and American Leaders
In 2021, sending a warning message to China, former Japanese Prime Minister Shinzo Abe categorically stated:
An armed invasion of Taiwan would be a grave danger to Japan. A Taiwan emergency is a Japanese emergency, and therefore an emergency for the Japan-US alliance. People in Beijing, President Xi Jinping in particular, should not have a misunderstanding in recognizing this.
From this statement it is evident that China’s increasing military activism over Taiwan has provided an impetus to the United States and Japan. In reaffirming on April 16, 2021 that the US-Japan Alliance has “become a cornerstone of peace and security in the Indo-Pacific region and around the world,” Biden and then-Japanese Prime Minister Yoshihide Suga issued a US-Japan Joint Leader’s Statement titled “U.S.-Japan Global Partnership for a New Era.” Specifically, the readout stated: “We underscore the importance of peace and stability across the Taiwan Strait and encourage the peaceful resolution of cross-Strait issues.” This marked the first such explicit mention of “Taiwan” in a US-Japan leader’s statement—however, the precursor to it was set with the US-Japan 2+2 Dialogue in March 2021, which “underscored the importance of peace and stability in the Taiwan Strait.” Criticizing the Biden-Kishida Summit, China’s Foreign Ministry responded, saying:
We have taken note of some of the developments at the summit of the leaders of the United States and Japan, which, despite China’s serious concerns, have launched smear campaigns against China on issues such as Taiwan and maritime affairs, and have grossly interfered in China’s internal affairs, in serious violation of the basic norms of international relations.
Image: Japanese Prime Minister Fumio Kishida (at podium) and US President Joseph Biden (right) appear together for public remarks during their White House summit (April 10, 2024). (Image source: Japan Prime Minister’s Office)
Agreements between the United States, Japan, China, and Taiwan
Of note, both Washington and Tokyo officially maintain a position of strategic ambiguity towards the issue of Taiwan’s sovereignty given their acknowledgement of a “One China Policy.” The Joint Communique between Washington and Beijing (Normalization Communique) signed on January 1, 1979 outlines:
The United States of America recognizes the Government of the People’s Republic of China as the sole legal Government of China. Within this context, the people of the United States will maintain cultural, commercial, and other unofficial relations with the people of Taiwan. [….] The Government of the United States of America acknowledges the Chinese position that there is but one China and Taiwan is part of China.
Similarly, the Joint Communique between Tokyo and Beijing signed on September 29, 1972 outlines:
The Government of Japan recognizes that Government of the People’s Republic of China as the sole legal Government of China. The Government of the People’s Republic of China reiterates that Taiwan is an inalienable part of the territory of the People’s Republic of China. The Government of Japan fully understands and respects this stand of the Government of the People’s Republic of China, and it firmly maintains its stand under Article 8 of the Postsdam Proclamation.
Despite having no formal diplomatic ties, the US government maintains a “robust unofficial relationship” with Taiwan, and under the 1979 Taiwan Relations Act considers “any effort to determine the future of Taiwan by other than peaceful means a threat to the peace and security of the Western Pacific area and of grave concern.” Despite the lack of formal diplomatic ties, this Act makes the provision that the United States “will make available to Taiwan such defense articles and defense services in such quantity as may be necessary to enable Taiwan to maintain a sufficient self-defense capability.” For instance, in June 2024, the Biden administration approved a new USD $360 million weapons sale to Taiwan—which includes 291 Altius-600M systems (drones with warheads) and 720 Switchblade drones known as “extended-range loitering munitions.” In Washington’s view, the sale:
[S]erves US national, economic, and security interests by supporting the recipient’s [Taiwan] continuing efforts to modernize its armed forces and to maintain a credible defensive capability. It will help improve the security of the recipient and assist in maintaining political stability, military balance, and economic progress in the region.
While Japan does not directly sell arms to Taiwan, it has prioritized its security alliance with the United States to collaborate on joint exercises or defense planning related to Taiwan. For instance, in the context of China’s intensified military activities around Taiwan, Japan’s 2021 defense white paper posited:
[T]he United States has demonstrated a clear stance of supporting Taiwan in military aspects, such as transits by U.S. vessels through the Taiwan Strait and weapon sales. Stabilizing the situation surrounding Taiwan is important for Japan’s security and the stability of the international community. Therefore, it is necessary that we pay close attention to the situation with a sense of crisis more than ever before.
This brings into perspective the direct correlation between the United States and Japan on the issue of Taiwan. That is, in the post-World War II period, Japan’s Taiwan policy has been conditioned by the American containment strategy—as a result of which, it is influenced by Washington’s political orientation towards Taiwan. This was reflected in the military alliance between Tokyo and Washington, as codified in the first version of the Treaty of Mutual Cooperation and Security, signed in 1951. According to Article I of the Treaty:
The Parties undertake, as set forth in the Charter of the United Nations, to settle any international disputes in which they may be involved by peaceful means in such a manner that international peace and security and justice are not endangered and to refrain in their international relations from the threat or use of force against the territorial integrity or political independence of any state, or in any other manner inconsistent with the purposes of the United Nations.
Modern Developments in US-Japan Security Cooperation
The scope of the alliance was further expanded with the 1997 US-Japan Defense Guidelines, which broadened the alliance’s focus: from the defense of Japan, to that of responding to “situations in areas surrounding Japan.” There is a direct correlation between the US-Japan alliance and peace and stability in the Asia-Pacific region (now known as the Indo-Pacific region). In this matrix, Taiwan looms large in the security calculus of the US-Japan alliance. In case of a conflict in the Taiwan Strait, if the United States decides to intervene, it is only natural for Japan to also become involved. For instance, in the aftermath of China’s missile tests in the Taiwan Strait in 1996, Japan reaffirmed its alliance with the United States and provided logistical support for American military operations in the Taiwan Strait under the revised 1997 guidelines given the expansion of the focus of the alliance from the defense of Japan to the maintenance of peace and stability in the region. More recently, from June 7-18 this year, for the first time Japan’s Self-Defense Forces joined the US military’s Valiant Shield exercise—one of America’s largest warfighting exercises in the Pacific, which can be read as a response to China’s Joint Sword-2024A exercise around Taiwan in May. Thereby, in tackling the China challenge, this joint military exercise provided a further boost to the US-Japan alliance’s deterrence and response capabilities.
China’s growing military capabilities and aggressive posturing have pushed Taiwan into the spotlight of the US-Japan Alliance. Balancing support for Taiwan with avoiding actions that could provoke China remains a challenge. So far, both Washington and Tokyo have been navigating the complex situation strategically by balancing their interests and seeking to maintain regional stability. Thereby, if Taiwan is attacked, in all possibility, the United States will intervene and Japan will follow—as neither the United States nor Japan will cater to Beijing’s demands at Taipei’s expense.
The main point: China’s increasingly aggressive posture towards Taiwan has raised significant concerns for the United States and Japan. Although balancing support for Taiwan while avoiding provocative actions remains a challenge, both Washington and Tokyo have strategically navigated the situation in the past—and neither will cater to Beijing’s demands at Taipei’s expense.
