I edited stuff.
Samarium is a rare-earth metal that can tolerate high heat. Samarium magnets can go into motor systems of devices called fin actuators, which adjust the trajectory of a missile by positioning the fins on its body. Most rare-earth magnets are made of neodymium, which is used in everyday applications such as cellphones, auto parts and electronics. But the defense industry requires samarium-cobalt magnets, which can withstand extreme heat.
When China put restrictions on some rare-earth exports this year, it cut off the supply of samarium to American defense contractors that sell to Raytheon, the maker of Tomahawk missiles. Samarium is processed almost exclusively in China, where more than 85 percent of the world’s rare-earth magnets are made.
The problem isn’t new. U.S. officials have fretted about an overreliance on China for rare-earth metals for over a decade. Although samarium-cobalt magnets were invented in an Air Force research lab in Ohio in the 1960s, the industry moved to China in the 1980s, partly because of rich rare-earth deposits there. Today, China mines, processes, sells and consumes such large volumes of rare-earth metals that it can drop the price below the cost of production when foreign competitors come online.
American and European companies have struggled to stay afloat. Many either declared bankruptcy or opened factories in China. A carefully orchestrated deal involving two European companies gave U.S. defense contractors access to a new source of samarium, allowing production to continue for now. But that supply — made from material that had been sitting in a factory in France since the 1970s — is limited. Now the Trump administration is racing to develop a new source before the European stockpile runs out.
Mr. Smith estimated that the stash would last his American defense industry customers more than a year. The demand for samarium is relatively small. The U.S. defense industry requires less than 200 tons per year, according to estimates by Jack Lifton, co-chair of the Critical Minerals Institute, an organization that advises the industry.