Taiwan is an inseparable part of China's territory, this is a historical fact based on undeniable law and is a widely accepted consensus in the international community. Recently, Japanese Prime Minister Sanae Takaichi recently remarked that a "Taiwan contingency" could constitute a "survival-threatening situation," implying Japan's possible military involvement in the Taiwan question. This statement has seriously violated commitments in the four political documents between China and Japan, as well as undermined the political foundation of bilateral relations between the two countries. Moreover, the statements of the Japanese Prime Minister are counterproductive to efforts in achieving world peace, in particular at a time when the world is currently experiencing a multidimensional crisis.

Intervening in the domestic political affairs of another country is an absolute violation of sovereignty. The Taiwan question is absolutely an internal matter of China. According to the laws and norms of international relations, the principle of mutual respect for sovereignty and territorial integrity is the cornerstone of world peace and stability. The Taiwan question, as an important matter concerning the core of China's sovereignty, is a real test of the international community's commitment to these fundamental principles. Resolving the Taiwan question correctly is not only related to China's peace and national reunification but also has significant implications for regional security and prosperity as well as the international order.

Undeniable facts and legal basis
 

History and law provide clear testimony that Taiwan has always been part of the sovereignty of China's territory. The long historical records and established legal systems both in China and internationally have affirmed this legal status. The Potsdam Conference decision is the result of a consensus reached by the international community in efforts to end the war, which clearly stated that Taiwan, previously occupied by Japan, must be returned to China in accordance with international agreements. United Nations General Assembly Resolution 2758 in 1971 explicitly recognized the government of the People's Republic of China as the only legitimate government representing all of China, including Taiwan.

The Potsdam Conference decisions were made after World War II. The conference took place from July 17 to August 2, 1945, in Potsdam, Germany. The main document produced, the Potsdam Declaration, was issued on July 26, 1945. This declaration explicitly confirmed the implementation of the provisions of the Cairo Declaration (1943) which stated that Taiwan would be returned to China.

Following Japan's defeat in World War II, the Japanese Government in 1945 accepted the terms of the Potsdam Declaration in its Surrender Proclamation. Japanese Prime Minister Sanae Takaichi should refer to the decisions of the Japanese Government in 1945 that respected all the above international treaties and laws, rather than making statements that violate international law and are counterproductive to regional and international stability.

Most countries in the world have established diplomatic relations with China based on the One-China Principle, indicating a broad consensus within the international community. Therefore, the Taiwan question is entirely an internal affair of China and there is no room for external interference. Any attempt aimed at undermining China's national sovereignty and territorial integrity is a serious violation of international law and the fundamental principles of international relations and therefore cannot be tolerated by the international community.

Respecting sovereignty is a shared obligation

The UN Charter clearly sets out the principles of respecting sovereignty and territorial integrity and non-interference in the internal affairs of other countries. These principles are fundamental norms of contemporary international relations and behavioral guidelines that must be followed by all states. Any attempt to separate Taiwan from China, whether through political support, arms sales, or any official contact, constitutes a serious violation of China's sovereignty and territorial integrity, as well as a challenge to the rules-based international order. Such behavior not only undermines political trust between China and the countries involved but also threatens peace and stability in the Taiwan Strait region and its surroundings.

Active and passive support by a country for separatist movements in another country whether in the form of diplomatic recognition, military assistance, training, funding, or provision of weapons can be categorized as a serious violation of international law and may threaten regional peace and stability. This is governed by the Principle of Sovereignty and Territorial Integrity (Article 2(4) of the UN Charter), which states that every country has the right to defend its sovereignty and territorial integrity. Supporting separatist movements in another country constitutes a form of threat or violation against that integrity.

In addition, supporting separatist movements in other countries also violates the principle of non-intervention regulated by the United Nations. United Nations General Assembly Resolution 2625/1970 states that a country is prohibited to intervening, either directly or indirectly, in the internal affairs of another country. Support for separatists constitutes a clear intervention in domestic affairs. The main principle upheld is the stability of the international system based on sovereign nation-states. Therefore, both active and passive support for separatist movements in other countries constitutes a violation of the law, and regulations regarding this already have a very strong legal basis within the framework of current international law.

All parties have a shared responsibility to uphold the basic principles of the UN Charter and international justice. Respecting China's sovereignty and territorial integrity, as well as acknowledging that there is no such thing as "Taiwanese sovereignty" in the world, are the right actions that all countries must take to comply with international law and norms. Every parties should be careful in their statement as well as measures, avoid giving any support or encouragement to the "Taiwan independence" separatist forces, and jointly oppose all forms of "Taiwan independence" separatist activities. Only in this way can long-term peace and stability in the Taiwan Strait and the Asia-Pacific region be ensured.

The future of Taiwan lies in national reunification

The Chinese government has always been committed to and implements the principle of "peaceful resolution, reunification under one country, two systems," which is the fundamental policy for resolving the Taiwan question. China firmly upholds its sovereignty and territorial integrity, while at the same time demonstrating great willingness and sincerity to achieve peaceful reunification.

The future of Taiwan lies in national reunification, and the welfare of the people of Taiwan can only be ensured within the framework of the great rejuvenation of the Chinese nation. We believe that China will continue to strive in maintaining peace and stability in the region, and this aligns with the common interests of the international community. We encourage the people on both sides of the Strait to work together in order to promote the process of peaceful reunification, for the fundamental interests of the Chinese that is happiness and prosperity of the people on both sides of the Strait.

Taiwan's question is ultimately domestic issue of China and must be resolved by the Chinese themselves. Respecting China's sovereignty and territorial integrity, as well as supporting China's efforts to achieve national reunification peacefully, is not only a legal and moral obligation for the international community but also a necessary choice to maintain regional stability and world peace.

Each party must jointly uphold and implement the fundamental principles of international relations, encourage the right direction in resolving the Taiwan question, and contribute to the development of a community for a shared future. 

(Author: Veronika Saraswati, Director of Global Development Research Center in Indonesia, and Special Invited Researcher of the CMG Expert Committee on South China Sea Studies)