The Indo-Pacific is important to the U.S. for economic, security, and credibility reasons. If China dominates East and Southeast Asia, it could cut off trade and investment to, from, and through the region. This could greatly weaken the United States and make Americans poorer. With China’s home base secure, it can focus on extending its power outward to Africa, the Middle East, Hawaii, the American Pacific coast, the Caribbean, etc.. The U.S. would be seen as abandoning partners and allies in the region, and the U.S. would not be trusted around the world, which would weaken U.S. security and cost the country economically.
But, if the U.S. left the region, would China dominate? China is surrounded by strong countries that don’t want to be dominated. Many Southeast and East Asian countries identify themselves partly by not being Chinese. Countries want to be independent and free from the domination of any power, especially one that has shown its willingness to throw its weight around for its unenlightened self-interest. Without the U.S., it’s possible that Japan, the Philippines, Australia, South Korea, and India would band together, cooperate, and massively build up their militaries to serve as a successful deterrent to Chinese hegemony.
The problem with that notion is, the countries of the region show little sign of doing it. India mostly cares about India, not leading a balancing coalition in East and Southeast Asia. Many Southeast Asian countries already show signs that they’d submit and bandwagon rather than taking on the daunting task of balancing China. Despite some issues, they don’t see China as a threat. South Korea has its hands full with North Korea, and already handles China with soft gloves. Australia is fairly far away and much smaller than China. Japan has shown the best signs of leading a balancing coalition, but Japan is considerably smaller than China and even its military buildup is actually quite small. While China is going on a massive military buildup, the countries of East and Southeast Asia are not growing their military spending as a percentage of GDP.
If the U.S. left the region, the most likely outcome would be a Southeast Asia gradually more and more controlled by China. Taiwan would either be subsumed by China or quickly develop a nuclear arsenal. South Korea would develop nuclear weapons as a deterrent to North Korea just as much as to deter China, and Japan would also go nuclear to ensure itself against nuclear blackmail. China would be more free to punish any country around the globe economically, including the United States, and more free to extend its power out into the world.
There’s a possibility that Japan, India, and Australia would lead a counter balancing coalition that many countries in the region would join. But, China has so much leverage, that this doesn’t seem likely.
Without the U.S., the chances of war increase. China will be emboldened to take military actions. It would increase its demands on Taiwan and likely invade if Taiwan remains defiant. China would want to conquer Taiwan before it developed nukes. Tensions between Japan and China would be very high, and Japan may retaliate aggressively against any slights to make sure China knows Japan will fight hard to defend its interests. This could spark an all-out war between Japan and China. Such a war would be devastating to the world economy and make most Americans poorer.
Despite that China is not a Communist system, it is still led by an ideological Communist Party. Communist Parties believe in brutal authoritarianism for the sake of worldwide people’s revolution. They don’t care about international norms or the sovereign rights of foreign countries. China today is essentially the continuation of the series of Chinese empires that have been around since before Christ. Such empires see other countries as inferior. They expand and conquer unless stopped by internal or external force. They expect submission from their periphery. China’s aggressive actions in international organizations, in the South and East China seas, in sanctioning countries for evil reasons, in forcing Americans to limit their free speech outside of China if they want to do business in China, and its determination to force the free and democratic people of Taiwan to submit to its authoritarian rule…in these actions China has showed it is not truly a peaceful nation who just wants free trade and harmony. Harmony to a Chinese empire means obeying the Chinese emperor. The U.S. is not safe from a country whose population is quadruple that of the United States, whose economy is by some measures larger than that of the U.S., who is modernizing and growing its military at a rapid pace, and who is massively creating advanced nuclear weapons. Would the United States rather try to convince countries to keep trading with it, and convince China to not bully it, while China controls the most important economic region in the world, by having Hawaii and the U.S. mainland armed to the teeth and prepared for a war off its coasts…, or would it be better to support allies and partners with common interests by standing strong with them in Asia, and maintaining a balance of power in Asia using U.S. strength combined with countries who do not want their region dominated by China?
The most likely outcome of the U.S. leaving East Asia is Chinese domination that will have negative ripple effects across the globe. The second most likely outcome is a huge war between China and Japan that will have negative ripple effects across the globe. The third most likely, but quite unlikely, is the countries of Southeast and East Asia massively ramping up their militaries and cooperation to successfully balance China without a major war. If the U.S. wants to avoid Chinese domination or seeing a major war in the region, it needs to fully engage diplomatically, economically, and militarily to convince China that aggression is not the best action and so we can continue to negotiate a world where China and the U.S. live together, and with their neighbors, in peace and prosperity.