A Taiwan Strait crisis will be initiated by China, with the aim of “changing the status quo by force.” In this crisis, since the battlefield will extend to the East China Sea and waters and airspace around Taiwan, Japan will basically have to deal with this as its own contingency, invoking its right to individual self-defense. Although the extent of U.S. involvement in such a crisis is still uncertain, this will occur as the consummation of the U.S.-China rivalry. In this situation, Japan will have the obligation to provide direct or indirect military cooperation to its ally, the U.S., under the Guidelines for Japan-U.S. Defense Cooperation.
Similar to Russia's intimidation of the neighboring countries during its invasion of Ukraine, when China launches a military invasion of Taiwan, it will sternly intimidate Japan by asserting that, “The unification of Taiwan is China's internal affair. If Japan participates in any form of military intervention relating to Taiwan's reunification by the U.S. and other countries, it will be regarded as a major threat to China's security and become a target of attacks, including by nuclear weapons.” Japan's explanation of its domestic policy, including the three non-nuclear principles, will be meaningless in the face of China's nuclear threat. It will have to choose between two policy options: “be subservient to China or fight against China with the U.S.”
It is not realistic for Japan, a non-nuclear power that does not even have a full-scale military by international standards, to respond singlehandedly to the military threat from China, which possesses nuclear arms. The rational option will be to invoke the Japan-U.S. alliance to fight with its ally, the U.S., to safeguard its security. It goes without saying that the people's support will be indispensable for this policy option since this will bring about a national crisis in which Japan may become a target of China's nuclear attack.
The Japanese people – including, of course, the political leaders – have minimal basic knowledge of security. This lack of basic knowledge for them to think about a national crisis is because there has not been any need for them to seriously consider national security as a personal matter, and there have been no broad-ranging educational and research efforts. Relations between the political and military authorities, which constitute the core of strategies and tactics in a national crisis, have also been regarded as taboo. There has not been any real effort to face this issue squarely. The way Japan responded to the Great East Japan Earthquake and the Covid pandemic shows that Japan, as a nation and as a society, is extremely vulnerable in a national crisis. Governance regarding the structures, legal systems, and organizational culture for protecting the people during a national crisis is decisively insufficient. Even during the drafting of the three new strategic documents in 2022, there was hardly any extensive basic debate on security in the Diet and elsewhere, which was decisively lacking in Japan. As the premise for thinking about a national crisis, every Japanese citizen needs to know about the basic theories of national security, such as the concept of state, why is national defense necessary, and the fact that the defense of the country comes with risks.
One of the major lessons learned from Japan's defeat in the Pacific War is that there was hardly any (open) discussion of major security issues by the administration, the military, the Diet, and the people in the 1930s, and these four sectors did not share a common understanding. Japan was dragged into starting the war by the opinion of certain hardliners despite the awareness that Japan would lose the war. The situation is almost the same at present; no national debate—i.e. discussion in the Diet or among the people—is taking place on the basic direction of Japan's security (for example, how to deal with China's nuclear threat in concrete terms).
Deliberations in the Diet so far on a Taiwan Strait crisis seem to have mostly consisted of theories of what should be—such as “if a Taiwan Strait crisis occurs, that will be the end of Japan, so the only important thing is to prevent such a crisis”—and abstract discussions. The U.S. may possibly not get deeply involved in this crisis. China will continue to exist after a Taiwan Strait crisis, and while the U.S.-China relationship may become hostile for a while, they will continue to maintain a certain level of state relationship. How should Japan, which is geopolitically close to China and bound to face China's military threat directly, deal with such a situation? The political leaders have a serious responsibility to explain to the people why Japan must fight against China to win their understanding and support.