Under the leadership of Xi Jinping, China’s authoritarian and dictatorial leftist ideology is becoming more and more apparent, coupled with the external expansionism under the manipulation of national consciousness, which has made the international community more alert to the threat of China, while the recognition and sympathy for a free and democratic Taiwan are increasing. Cross-strait relations continue to be tense and confrontational due to the polarized perceptions of state sovereignty between the two governments. Beijing is actively using the “gray zone conflict” to exert pressure on Taiwan, and Chinese military aircraft and warships are harassing Taiwan in numerous ways and with record frequency. In the face of China’s increasingly assertive stance and the threat of force, Taiwan continues to maintain its “status quo” cross-strait policy on the one hand and actively demonstrates its determination to defend itself as a pivotal deterrent to China’s advances on the other. To this end, this chapter intends to analyze the critical developments of Taiwan’s regional security in 2021 in terms of Taiwan’s mindset of seeking stability under the cross-strait impasse, Taiwan’s response under the new Biden administration, and the rising internationalization of Taiwan Strait issues.