Nations, especially great powers, sometimes appear to commit to means that are disproportionate to the end goals. One example is risking nuclear war that could entail the extinction of the human race over limited regional conflicts, such as what had almost occurred several times during the Cold War. This is often characterised as irrational and denigrated as the fear of losing face or national prestige. But if psychologists have taught that what looks rational may be irrational, it may also work the other way in politics. By threatening to do the irrational, you demonstrate total commitment, and so hope to avoid doing the unthinkable. On October 1, Chinese forces dispatched 38 warplanes into Taiwan’s self-declared air defence identification zone (ADIZ). In total, over four days, nearly 150 aircraft were sent. It’s not that mainland China wants to start a war or threaten an invasion. It’s precisely to avoid one. Taiwan must ‘resist annexation’, Tsai Ing-wen says “To achieve the reunification of the motherland by peaceful means is most in line with the overall interests of the Chinese nation, including our compatriots in Taiwan,” said President Xi Jinping in a commemoration of the 110th anniversary of the 1911 Chinese revolution. By implication, independence will be the end of peace. For all its criticism of mainland China over Taiwan, Washington ought to understand what Beijing is doing. Two words: credibility and deterrence. Whenever Washington is criticised for doing something crazy or excessive, those who work in the foreign policy establishment inevitably explain it as “the need to maintain American credibility and to deter the enemy”. It’s the same with Beijing, even though its credibility is mainly confined to the region, not the entire world, as with the Americans. And it is to deter Taiwan independence. Beijing must maintain the credibility of its threat that it will go to war over that. How close to an actual declaration of independence would amount to a casus belli is entirely up to Beijing to decide, though Washington and Taipei can guess. That’s the mainland’s answer to those secessionists-in-disguise such as President Tsai Ing-wen, who try to “salami-slice” their way towards independence. Washington, too, wants to maintain the credibility of its commitment to defend the island in the event of a mainland invasion. But a war across the Taiwan Strait will be an existential struggle for Chinese people, not Americans. Which side do you think will be fully committed?