A major war in the Indo-Pacific is probably more likely now than at any other time since World War II.

The most probable spark is a Chinese invasion of Taiwan.

President Xi Jinping of China has said unifying Taiwan with mainland China “must be achieved.”

His Communist Party regime has become sufficiently strong — militarily, economically and industrially — to take Taiwan and directly challenge the United States for regional supremacy.

The United States has vital strategic interests at stake.

A successful Chinese invasion of Taiwan would punch a hole in the U.S. and allied chain of defenses in the region, seriously undermining America’s strategic position in the Western Pacific,

and would probably cut off U.S. access to world-leading semiconductors and other critical components manufactured in Taiwan.

As president, Joe Biden has stated repeatedly that he would defend Taiwan.

But leaders in Washington also need to avoid stumbling carelessly into a war with China because it would be unlike anything ever faced by Americans.

U.S. citizens have grown accustomed to sending their military off to fight far from home.

But China is a different kind of foe — a military, economic and technological power capable of making a war felt in the American homeland.

As a career strategic analyst and defense planner, including for Australia’s Defense Department, I have spent decades studying how a war could start, how it would play out

and the military and nonmilitary operations that China is prepared to conduct.

I am convinced that the challenges facing the United States are serious, and its citizens need to become better aware of them.

The military scenario alone is daunting: China would probably launch a lightning air, sea and cyber assault to seize control of key strategic targets on Taiwan within hours,

before the United States and its allies could intervene.

Taiwan is slightly bigger than the state of Maryland; if you recall how quickly Afghanistan and Kabul fell to the Taliban in 2021,

you start to realize that the takeover of Taiwan could happen relatively quickly.

China also has more than 1,350 ballistic and cruise missiles poised to strike U.S. and allied forces in Japan, South Korea, the Philippines and American-held territories in the Western Pacific.

Then there’s the sheer difficulty the United States would face waging war thousands of miles across the Pacific against an adversary that has the world’s largest navy and Asia’s biggest air force.

Despite this, U.S. military planners would prefer to fight a conventional war.

But the Chinese are prepared to wage a much broader type of warfare that would reach deep into American society.

Over the past decade, China has increasingly viewed the United States as mired in political and social crises.

Mr. Xi, who likes to say that “the East is rising while the West is declining,” evidently feels that America’s greatest weakness is on its home front.

And I believe he is ready to exploit this with a multipronged campaign to divide Americans and undermine and exhaust their will to engage in a prolonged conflict

— what China’s military calls enemy disintegration.

Over the past two decades, China has built a formidable cyberwarfare capability designed to penetrate, manipulate and disrupt the United States and allied governments,

media organizations, businesses and civil society.

If war were to break out, China can be expected to use this to disrupt communications and spread fake news and other disinformation.

The aim would be to foster confusion, division and distrust and hinder decision making.

China might compound this with electronic and probably some physical attacks on satellites or related infrastructure.

These operations would most likely be accompanied by cyber offensives to disrupt electricity, gas, water, transport, health care and other public services.

China has demonstrated its capabilitiesalready, including in Taiwan, where it has waged disinformation campaigns, and in serious hacking incidents in the United States.

Mr. Xi has championed such subterfuge as a “magic weapon.”

China could also weaponize its dominance of supply chains and shipping.

The impact on Americans would be profound.

The U.S. economy is heavily dependent on Chinese resources and manufactured goods, including many with military applications, and American consumers rely on moderately priced Chinese-made imports for everything from electronics to furniture to shoes.

The bulk of these goods is transported aboard ships along sea lanes increasingly controlled by Chinese commercial interests that are ultimately answerable to China’s party-state.

A war would halt this trade (as well as American and allied shipments to China).

U.S. supplies of many products could soon run low, paralyzing a vast range of businesses.

It could take months to restore trade, and emergency rationing of some items would be needed.

Inflation and unemployment would surge, especially in the period in which the economy is repurposed for the war effort, which might include some automobile manufacturers switching to

building aircraft or food-processing companies converting to production of priority pharmaceuticals.

Stock exchanges in the United States and other countries might temporarily halt trading because of the enormous economic uncertainties.

The United States might be forced to confront the shocking realization that the industrial muscle instrumental in victories like that in World War II

— President Franklin Roosevelt’s concept of America as “the arsenal of democracy” — has withered and been surpassed by China.

China is now the dominant global industrial power by many measures.

In 2004 U.S. manufacturing output was more than twice China’s; in 2021, China’s output was double that of the United States.

China produces more ships, steel and smartphones than any other country and is a world leader in the production of chemicals, metals, heavy industrial equipment and electronics

— the basic building blocks of a military-industrial economy.

Critically, the United States is no longer able to outproduce China in advanced weapons and other supplies needed in a war, which the current one in Ukraine has made clear.

Provision of military hardware to Kyiv has depleted American stocks of some key military systems.

Rebuilding them could take years.

Yet the war in Ukraine is relatively small-scale compared with the likely demands of a major war in the Indo-Pacific.

So what needs to be done?

On the military front, the United States should accelerate programs already underway to strengthen and disperse American forces in the Western Pacific to make them

less vulnerable to attacks by China.

At home, a concerted effort must be made to find ways to better protect U.S. traditional and social media against Chinese disinformation.

Supply chains of some critical goods and services need to be reconfigured to shift production to the United States or allied nations, and the United States must pursue

a longer-term strategic drive to restore its dominance in global manufacturing.

Building a stronger deterrence by addressing such weaknesses is the best means of averting war.

But this will take time.

Until then, it is important for Washington to avoid provocations and maintain a civil discourse with Beijing.

The high-altitude balloon that drifted across the United States this month was seen by many Americans as a shocking Chinese breach of U.S. sovereignty.

It may turn out to be child’s play compared with the havoc China could wreak on the American homeland in a war.

By Ross Babbage

Dr. Babbage is the author of the forthcoming book “The Next Major War: Can the U.S. and Its Allies Win Against China?”

Ross Babbage is a nonresident senior fellow at the Center for Strategic and Budgetary Assessments in Washington and the C.E.O. of Strategic Forum in Canberra, Australia. He has served in a number of Australian government agencies and been a senior adviser to several Australian defense ministers.