The Taiwan question is the most important and most sensitive issue at the very core of China-US relations. It concerns China’s sovereignty, territorial integrity and national dignity, and as such it is China’s internal affair. Any attempt by external actors to intervene, particularly through military means, strikes at the core of China’s domestic politics. Against this backdrop, the United States’ recent announcement of large-scale arms sales to China’s Taiwan region marks a serious escalation that cannot be dismissed as routine or benign.The legal and political status of Taiwan is unambiguous. There is but one China in the world. Taiwan is an inalienable part of China’s territory, and the government of the People’s Republic of China (PRC) is the sole legal government representing the whole of China. This is not a matter of competing narratives or selective interpretation. It is the recognised basis upon which the PRC established diplomatic relations with the US and the majority of the international community. This constitutes the true status quo across the Taiwan Strait, and it is this status quo that has provided the essential framework for peace and stability over decades.The US formally acknowledged this reality when it normalised relations with China in 1979. In the Joint Communiqué on the Establishment of Diplomatic Relations, Washington recognised the government of the PRC as the sole legal government of China and acknowledged the Chinese position that Taiwan is part of China. These commitments were the prerequisite for the establishment of diplomatic ties. They were reinforced in the August 17, 1982 Joint Communiqué, which remains a cornerstone of bilateral relations.In that document, the US explicitly stated that it had no intention of infringing upon China’s sovereignty and territorial integrity, no intention of interfering in China’s internal affairs, and no intention of pursuing a policy of “two Chinas” or “one China, one Taiwan”. Of particular importance, it declared that it did not seek to carry out a long-term policy of arms sales to Taiwan and that it intended gradually to reduce such sales, leading to a final resolution of the issue. These were clear policy undertakings designed to prevent the Taiwan question from becoming a source of sustained conflict.The current albeit unfortunate trajectory of US policy stands in direct contradiction to those commitments. Successive and increasingly expansive arms sales to Taiwan, justified under the slogan of “maintaining the status quo”, represent a steady hollowing-out of the one-China principle. Rather than contributing to stability, such actions embolden separatist forces on the island and weaken the already fragile strategic trust between Beijing and Washington. To claim that these moves are defensive is to ignore their cumulative effect and their political signalling.By continuing to arm Taiwan, the US sends a dangerously misleading signal to advocates of “Taiwan independence”, encouraging the illusion that external backing can offset historical reality and international law. This is a false promise. No quantity of advanced weaponry can change the fact that China’s reunification is an irreversible historical trend. What such sales can do is increase the risk of misjudgement and push the region closer to confrontation.China’s recent decision to impose countermeasures against US military-related companies and senior executives involved in these arms sales reflects the seriousness of the situation. Taken in accordance with China’s Law on Countering Foreign Sanctions, these measures target those who have directly profited from actions that undermine China’s sovereignty and security interests. They are not an end in themselves but a necessary response to repeated violations of clear political commitments. Any company or individual that chooses to participate in arming Taiwan must be prepared to face the consequences of that choice.The broader implications for China–US relations are equally stark. It is neither credible nor sustainable for the US to claim that it seeks cooperation with China on global challenges while simultaneously crossing China’s most sensitive red line. The Taiwan question admits of no ambiguity. Continual infringement upon China’s core interests inevitably erodes mutual trust and narrows the space for dialogue. Therefore, the current approach is strategically self-defeating.Secondly, the consequences extend beyond bilateral relations. Peace and stability across the Taiwan Strait are essential to regional security and global economic stability. The real threat to that peace does not lie in China’s insistence on defending its sovereignty, but in separatist activities encouraged by external interference. Arming Taiwan heightens tensions, places the safety and well-being of Taiwan residents at risk, and increases the likelihood of conflict between major powers.The path forward is clear and grounded in existing agreements. The US must return to strict adherence to the one-China principle and the three China–U.S. Joint Communiqués, honour the commitments it has already made, and cease arms sales to China’s Taiwan region. Only by doing so can it contribute to a more predictable and constructive relationship with China.