Each F-35 Lightning II aircraft contains more than 900 pounds of rare earth elements. Each Virginia-class submarine has 9,200 pounds. Permanent magnets made from these materials are used to make Tomahawk missiles, Predator drones and the Joint Direct Attack Munition series of smart bombs.

Almost all of this material comes from China. The country accounts for nearly all of the world’s processing of heavy rare earths — whose critical magnetic and optical properties are vital for defense systems. It also produces about 90 percent of rare earth magnets, used in everything from electric motors to turbines and electronics, for civilian and military use.

After President Donald Trump raised a wall of tariffs against Chinese imports on April 2, China used this formidable source of leverage to retaliate: It suspended exports of six heavy rare earth elements as well as rare earth magnets. Thus, Trump’s trade war against China has come to endanger America’s national security.

Trump seems to have miscalculated the balance of forces in his trade war. When China is America’s only source for so many things — iPhones and minerals are only two examples — it can retaliate against tariffs in ways that hurt. This is probably why Xi Jinping, the Chinese leader, has not petitioned Trump for relief. Xi apparently would prefer that the U.S. president come to him.

But the miscalculation over rare earths is particularly problematic because it puts America’s military’s edge at risk. The White House must either ratchet down its hostility toward Beijing or quickly find an alternative supply. Given China’s control over the industry and the Trump administration’s evident distaste for stepping back when it comes to China, both options look to be long shots.

This quandary is not entirely of Trump’s making. The supply risk became obvious nearly 15 years ago, when Beijing imposed a seven-week embargo on exports of rare earth elements to Japan in a dispute over a Chinese fishing trawler caught in contested waters. Since 2023, China has restricted exports of strategic materials such as gallium, germanium and graphite to the United States.

Despite official warnings about the danger of depending on China for such critical materials and the need to diversify supplies, there has been limited U.S. government support for the rare earths industry.

Market forces alone won’t solve this problem. Investments in domestic mining and refining have made little sense because rare earths and magnets were always available from China at low cost. After China’s 2010 embargo on exports to Japan, the Obama administration encouraged Hitachi Metals to build a rare earths magnet factory in North Carolina. But the plant closed in 2015, after less than two years in operation.

Domestic capacity to produce rare earths is extremely limited. One mine in California is active. And the company that runs it, MP Materials, plans to ramp up domestic refining and has a magnet production facility coming online in Texas. But the trade war with China has put it in a bind, as it shipped most of its concentrates to China for processing. Another firm, Australia’s Lynas Rare Earths, is building a refinery for heavy rare earths in Texas, but it is struggling under high costs. USA Rare Earth has big plans but still nothing in production.

It’s hard to predict how China will play its hand. Its shipments of rare earths and magnets have been suspended while it puts in place an export licensing system for the materials. It is unclear how long this will take or how the licensing will operate.

The United States has few options. The Trump administration is investigating the risks of relying on imported minerals and their derivatives. But what Trump might do about the problem is unknown.

Tactics he has tried to obtain other critical minerals — shaking down Ukraine, threatening to take over Canada and Greenland, and inviting companies to mine the deep seabed in breach of international law — will not build the kind of goodwill needed to put together an international effort to find alternatives to China’s supply.

Tariffs seem especially counterproductive in this situation. Beijing’s retaliatory tariffs against the United States have already stopped exports of rare earths for processing in China.

Then there is the question of time. Various countries, including Australia, Brazil, South Africa and Vietnam, are looking into mining and refining rare earths and producing magnets.

But capacity outside China remains small. In the best of cases, it will take years, perhaps more than a decade, to build out an alternative rare earths supply chain.

The urgent question is how to manage until then. Given the circumstances, maybe launching a trade war against China, foreclosing on the possibility of cooperation and coexistence, was not such a good idea. Rare earths and magnets alone should motivate the president to reduce hostilities with China and start talking.