In retrospect, wars often seem unavoidable. Tensions built up. National ambitions clashed. Mutual fears and mistrust grew. Historical grievances simmered.

But in truth, they are never inevitable. They depend on decisions made by men – the leaders who ordered wars were almost always men – who could have chosen a different course of action.

I have been thinking about this a lot over the past year as I have been researching the threat of war between China and the United States and writing a new book about it.

The title of the English-language book, published by the International Institute for Strategic Studies and Routledge, is “Deterrence, Diplomacy and the Risk of Conflict over Taiwan.” However, the title of the translated (and expanded) Japanese version, also just translated by Fusosha, is “How to Stop World War Three,” which might be considered a somewhat dramatic title.

Would a war between the US and China really be considered “World War III”? And could it be prevented?

The answer to the first question is obvious: This would be the first war in history between two nuclear-armed superpowers, and it would be a war that would determine the nature of global leadership for decades to come.

With so much at stake, we must expect that such a conflict will spread to other countries, including Japan, and – sadly – ​​escalate to the point of using nuclear weapons.

The answer to the second question, however, is more reassuring and brings us back to the question of inevitability. If such a war were to break out, it would be the result of either

• a conscious calculation by one side regarding its chances of success, for example in the case of an invasion of Taiwan; or
• an impulsive reaction to an accident or incident, such as a collision in the South China Sea, where both sides failed to understand the other’s actions or intentions.

In both cases, the main issue is psychology and the decisions of political and military leaders. If such a catastrophic war is to be prevented, the focus must be on that psychology – and on how to change the decisions of leaders to keep the peace and avoid war.

This is one of the most important lessons from the war Russia started against Ukraine. First, Russia attacked the Ukrainian province of Crimea in 2014 and launched a large-scale invasion in February 2022.

This war would have been inevitable only if Russian President Vladimir Putin had decided, no matter the cost, to retake a former Russian colony that one of his Russian predecessors granted independence in 1991. That is what he chose to do, and Ukrainians and Russians are still suffering the consequences today.

Could he have been persuaded to make a different decision? Two years later, it seems that two things could have changed his calculations. First, if he had seen that the Ukrainian army was so well trained and equipped and so well supported by Ukrainian society that it was likely to offer sufficient resistance to make his invasion extremely costly and time-consuming.

This has indeed proved to be true, and that is why, more than two years later, he has managed to occupy only about 20 percent of Ukrainian territory, costing, by various estimates, 110,000 to 140,000 Russian soldiers their lives and a far greater number seriously injured. (And that is why Russia’s vulnerability has now been exposed by the daring counter-invasion of Ukraine.)

Putin expected the Ukrainian army to surrender easily, perhaps within a matter of days, so this must be considered a terrible miscalculation on his part. Had he known in advance what the cost would be and how little progress the Russian military would have made two years later, it is reasonable to doubt whether he would have ordered the invasion.

The second factor that could have changed his calculations was if he believed that American or other NATO forces would enter the war in support of Ukraine. In that case, President Joe Biden and other NATO leaders ruled out involvement of their forces from the outset, so Putin’s judgment on that was well-considered. And he has used the threat of using nuclear weapons to ensure that NATO leaders do not change their minds.

The war in Ukraine was a terrible tragedy and a terrible mistake by Russia and, not to forget, its “strategic partner” China. Russia and China signed a joint declaration on their goals and ambitions just three weeks before Putin ordered the full-scale invasion of Ukraine.

And yet there may be some good in this tragedy if the lessons learned from it can help prevent the outbreak of a far more catastrophic war in the Indo-Pacific.

The key point is that psychology is paramount. A Chinese attempt to invade or blockade Taiwan is inevitable only if the Chinese leadership decides to do so, not just talk about it. As Ukraine reminded us, this decision can be prevented in two ways.

The biggest advantage is that it can convince China’s leaders that, unlike in the case of Ukraine, American and other allied forces would quickly help Taiwan defend itself, so that China would fight against America and not just Taiwan. President Biden has said four times in 2021 and 2022 that he is committed to doing this. He said it precisely to prevent a copycat invasion of Taiwan.

Whoever wins the US presidential election in November should reiterate this commitment at the earliest opportunity, and then reiterate it again. Uncertainty about the intentions of a new president is the greatest threat to peace, because it could tempt President Xi Jinping to follow Putin by making miscalculations.

This commitment must be accompanied by an assurance that America remains opposed to a formal declaration of independence by Taiwan, but also by stronger language warning of the danger of mutual nuclear annihilation should war occur. The old framework of Cold War-era nuclear arms agreements must be revived for the US-China era.

In addition to such commitments, efforts must also be made to convince China that the defense forces in Taiwan and those in Japan, the Philippines, the US bases and South Korea are strong and agile enough to play a decisive and resilient role in the event of a conflict. If China concluded that an invasion would be a child’s play, it would be much more likely to attempt one.

This effort is underway in Japan and its allies, and the important thing is that such military build-ups continue year after year, decade after decade. The old Roman saying is unfortunately still true: if you want peace, prepare for war. The psychology of leaders and their decision-making depend on it.

Bill Emmott, former editor-in-chief of The Economist, is currently chairman of the Japan Society of the UK, the International Institute for Strategic Studies and the International Trade Institute.

This is a slightly expanded original English version of a column, “Jidai-no-Kaze” (Winds of Our Time), published in Japanese and English by Mainichi Shimbun and in English on Substack Bill Emmott’s Global View on August 11. It is republished with permission.