It is every president’s nightmare. The Chinese military is massing troops in Fujian Province and an armada offshore, just across the strait from Taiwan. According to U.S. intelligence, this buildup is no mere feint—Beijing is really preparing for war. Global stock markets are crashing, as the world faces what economists estimate could be a $10 trillion shock. The White House must suddenly answer a question it has long put off: Will it use military force to defend Taiwan?

This is not an outlandish hypothetical. Chinese President Xi Jinping has made clear that retaking Taiwan is essential to what his government calls “the great rejuvenation of the Chinese nation,” and Beijing is rapidly expanding its military. It is also just one of many scenarios that would result in a war involving Washington. China is threatening the United States’ treaty allies. Russia is menacing eastern Europe’s NATO members. Iran has accelerated its nuclear program. The odds that the United States might have to fight in a great-power war are higher today than at any point this century.

The U.S. military is arguably the most powerful in the world. But it is not ready for such a conflict. Its weapons are sophisticated. Its soldiers are second to none. Yet the United States has low stockpiles of munitions, its ships and planes are older than China’s, and its industrial base lacks the capacity to regenerate these assets. The U.S. supply of precision-strike missiles, for example, would last no more than a few weeks in a high-intensity conflict and would take years to replace. In war games that simulate a conflict in the Taiwan Strait, Washington runs out of key munitions within weeks.

American officials are aware of the shortages. In response, Congress and the Department of Defense have contracted to expand existing defense production lines and, in some cases, to restart old ones. Yet these recent efforts are insufficient to compensate for more than three decades of complacency and atrophy. Washington has hiked defense spending to $825 billion—a record nominal level. But this represents under three percent of U.S. GDP, the lowest level this century and among the lowest since World War II. Of that $825 billion, just 21 percent is dedicated to procuring new munitions and equipment.

To address this failure, Washington must act now. The Trump administration, in partnership with Congress, must undertake six urgent initiatives: modernizing existing assets, broadening defense capabilities, expanding stockpiles and manufacturing capacity for munitions, increasing competition and reducing supplier vulnerabilities, changing how the Pentagon does business, and increasing funding levels and continuity of funding. To be effective, these initiatives must be implemented together. A piecemeal approach will be insufficient. Increasing the American defense budget, for instance, is essential, but it will not be enough to meet U.S. needs unless Washington increases the number of companies in the defense industrial base and adds newer capabilities such as uncrewed systems, better space-based sensors, and software that can be continuously updated. Even then, American officials might struggle to get what they need unless the armed forces can more easily buy equipment and supplies from U.S. allies. Finally, the Pentagon needs to dramatically reform its management practices and procurement processes to focus on speed and efficacy.

Increasing defense spending may be a tough sell in Washington, given that both the Trump administration and progressives in Congress want to reduce the military’s footprint. But policymakers should remember that preventing a war is much cheaper than fighting one. With increased military spending on quantity and quality, Washington can make a potential Chinese invasion more costly and risky, creating doubt in Xi’s mind about his odds of succeeding. And if a U.S. military buildup does not stop a Chinese assault on Taiwan, Washington will be even happier that it expanded its arsenal. The United States, after all, will not have the time required to ramp up production once a conflict begins.

From 1989 to 1999, the United States cut its defense budget by nearly a third. The Cold War was over, so U.S. officials no longer saw the need for an enormous military. Congress continued to spend on major defense platforms, such as the F-22 aircraft and Nimitz-class aircraft carriers. But it drastically reduced the budget for munitions and smaller weapons. The defense industrial base consolidated, and its investment in capacity and workforce declined. Suppliers focused on minimum rates of production, just-in-time inventory management, and cost reductions.

None of this worried most U.S. strategists. After the first Gulf war, in which the United States defeated the sixth-largest army in six days with very few casualties, analysts assumed that future wars would likely be short and would not require massive stockpiles of basic munitions and materiel. Military planners assumed there would be future quick victories secured by technological superiority.

For three decades, this reasoning largely held. From 2001 to 2002, the United States drove the Taliban into exile, and it rapidly defeated the Iraqi military in the second Gulf war that began in 2003. But the resulting, lengthy insurgencies in Afghanistan and Iraq proved that this vision of quick victories was a fallacy. Instead, asymmetric capabilities and sustained political will helped the insurgents outlast the U.S. military. Russia’s 2022 invasion of Ukraine was further proof that the equation had changed. Defying the predictions of defense analysts, the Ukrainians successfully ground the wealthier, better-equipped Russian military to a halt, locking the two sides in a war of attrition that has cost thousands of lives and millions of munitions. Now, militaries are relearning the lessons of both world wars: major conflicts can still turn into slugfests, and industrial capacity is decisive.

The war in Ukraine also exposed just how bare Washington’s military cupboard is. U.S. officials have struggled to supply Kyiv with enough of the weapons it needs, and they have understandably fretted about their own defensive stocks. Although the exact number of missiles the United States has is classified, it is likely a few tens of thousands. Russia has fired almost 12,000 missiles in the last two years.

The American military suffers from munitions shortages across almost every weapons category. It lacks short- and medium-range missiles. Most important for a conflict in the Pacific, it has insufficient long-range precision missiles—such as the navy’s long-range antiship missiles, joint air-to-surface standoff missiles, and the army’s precision-strike missiles.........

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