The United States is a heartbeat away from a world war that it could lose. There are serious conflicts requiring U.S. attention in two of the world’s three most strategically important regions. Should China decide to launch an attack on Taiwan, the situation could quickly escalate into a global war on three fronts, directly or indirectly involving the United States. The hour is late, and while there are options for improving the U.S. position, they all require serious effort and inevitable trade-offs. It’s time to move with real urgency to mobilize the United States, its defenses, and its allies for what could become the world crisis of our time.

Describing the United States’ predicament in such stark terms may strike many readers as alarmist. The United States has long been the most powerful nation on earth. It won two world wars, defeated the Soviet Union, and still possesses the world’s top military. For the past year and a half, the United States has been imposing gigantic costs on Russia by supporting Ukraine—so much so that it seemed conceivable to this author that the United States might be able to sequence its contests by inflicting a decisive defeat-by-proxy on Russia before turning its primary attention to strengthening the U.S. military posture in the Indo-Pacific.

But that strategy is becoming less viable by the day. As Russia mobilizes for a long war in Ukraine and a new front opens in the Levant, the temptation will grow for a rapidly arming China to make a move on Taiwan. Already, Beijing is testing Washington in East Asia, knowing full well that the United States would struggle to deal with a third geopolitical crisis. If war does come, the United States would find some very important factors suddenly working against it.

One of those factors is geography. As the last two U.S. National Defense Strategies made clear and the latest congressional strategic posture commission confirmed, today’s U.S. military is not designed to fight wars against two major rivals simultaneously. In the event of a Chinese attack on Taiwan, the United States would be hard-pressed to rebuff the attack while keeping up the flow of support to Ukraine and Israel.

This isn’t because the United States is in decline. It’s because unlike the United States, which needs to be strong in all three of these places, each of its adversaries—China, Russia, and Iran—only has to be strong in its own home region to achieve its objectives.

The worst-case scenario is an escalating war in at least three far-flung theaters, fought by a thinly stretched U.S. military alongside ill-equipped allies that are mostly unable to defend themselves against large industrial powers with the resolve, resources, and ruthlessness to sustain a long conflict. Waging this fight would require a scale of national unity, resource mobilization, and willingness to sacrifice that Americans and their allies have not seen in generations.

The United States has fought multifront wars before. But in past conflicts, it was always able to outproduce its opponents. That’s no longer the case: China’s navy is already bigger than the United States’ in terms of sheer number of ships, and it’s growing by the equivalent of the entire French Navy (about 130 vessels, according to the French naval chief of staff) every four years. By comparison, the U.S. Navy plans an expansion by 75 ships over the next decade.

A related disadvantage is money. In past conflicts, Washington could easily outspend adversaries. During World War II, the U.S. national debt-to-GDP ratio almost doubled, from 61 percent of GDP to 113 percent. By contrast, the United States would enter a conflict today with debt already in excess of 100 percent of GDP.

Assuming a rate of expansion similar to that of World War II, it’s not unreasonable to expect that the debt could swell to 200 percent of GDP or higher. As the Congressional Budget Office and other sources have noted, debt loads on that scale would risk catastrophic consequences for the U.S. economy and financial system.

A global conflict would bring on other perils. Two U.S. rivals—Russia and Iran—are major oil producers. One recent report found that a prolonged closure of the Hormuz Strait amid a broader Middle Eastern conflict could push oil prices beyond $100 per barrel, substantially increasing inflationary pressures. China is a major holder of U.S. debt, and a sustained sell-off by Beijing could drive up yields in U.S. bonds and place further strains on the economy. It’s reasonable to assume that Americans would face shortages in everything from electronics to home-building materials.

All of that pales alongside the human costs that the United States could suffer in a global conflict. Large numbers of U.S. service members would likely die. Some of the United States’ adversaries have conventional and nuclear capabilities that can reach the U.S. homeland; others have the ability to inspire or direct Hamas-style terrorist attacks on U.S. soil, which may be easier to carry out given the porous state of the U.S. southern border.

If all of this sounds dreadful, well, that’s the point. As the biblical proverb says, fear is the beginning of wisdom. Global war is no longer a theoretical contingency debated by policy wonks, nor is it a fever dream of supposed hawks and militarists. It is a real and foreseeable, if not imminent, possibility.

The United States should be straining every nerve to prepare for this scenario in hopes of deterring conflict but ensuring that Americans are ready for it if it comes. Effective preparation is the path to improved deterrence; steps to increase readiness for war send a clear signal to adversaries that aggression is riskier to themselves than stability and peace.

The immediate priority for the United States has to be to ensure that Ukraine, Israel, and Taiwan have the weapons they need to defend themselves. These are the players with the most skin in the game at present. The best hope for avoiding a general conflict is that these frontier states will be so plucky and prickly that aggression is stopped or deterred before it can spread.

That won’t be possible unless the United States gets its defense-industrial base in order. Since the start of the Russia-Ukraine war, total U.S. defense production has increased by a mere 10 percent—even as the war demonstrates the staggeringly high consumption of military ammunition in a major conflict between industrial powers compared to the limited counterinsurgency operations of the recent past.

The situation is serious enough that Washington may need to invoke the Defense Production Act and begin converting some civilian industry to military purposes. Even then, the U.S. government may have to take draconian steps—including the rerouting of materials intended for the consumer economy, expanding production facilities, and revising environmental regulations that complicate the production of war materials—in order to get the U.S. industrial base prepared for mobilization.

It’s obvious that Washington will have to increase defense spending. The Biden administration’s flatlining of defense outlays, loading defense bills with domestic pork-barrel spending, and insistence on matching every dollar spent on the military with a dollar for climate policy or social spending is the wrong approach. To prepare for war without exploding the debt, Washington will have to pare back expenditures on social programs that enjoy broad popular support.

No one in the U.S. Congress wants to tell elderly constituents their benefits are being cut. But the alternative is to someday tell constituents why their children or grandchildren are being deployed to dangerous places without adequate weapons when war breaks out.

U.S. allies will also have to step up in significant new ways. The Ukraine war has prompted European NATO members, most notably Germany, to get more serious about security. Yet even now, fewer than one-third of them are fulfilling their commitment to spend at least 2 percent of GDP on defense. Major Western European members have yet to follow through on the promise they made more than a year ago at the bloc’s summit in Madrid to deploy brigade-sized units on NATO’s eastern flank.

Across the West, governments and citizens will have to reevaluate priorities that put their countries at a disadvantage in the coming struggle. It makes no sense for Americans to tie themselves to hasty and exceedingly expensive climate policies that sap economic growth at a moment when China is building coal-fired power plants at the rate of two per week. Europeans will have to rethink their aversion to nuclear energy; American progressives will have to rethink self-imposed restrictions that limit the United States’ ability to ramp up energy production.

Nothing on this list is easy. But the United States and its allies are entering a time of hard decisions. What’s happening in Ukraine and Israel would have seemed unimaginable even a few years ago, and more shoes are likely to drop in the days ahead. Americans and their allies need to start getting their affairs in order now so that they do not find themselves unprepared for a global conflict if it comes.