Look around you, and you’ll see rare earth elements at work. A phone vibrates because a magnet moves a weight. Its screen was polished with cerium powder. Its connection to the rest of the world crosses oceans on cables amplified with erbium. If you drove today, a rare earth magnet helped you steer, and a cerium compound scrubbed the exhaust.

All of these devices function because of 17 metals collectively known as rare earth elements. The scientists who gave the group that name in 1794 created a misnomer. Cerium alone is about as common in the Earth’s crust as copper.

However, separating rare earth minerals from one another and from raw ore is intensely difficult. As a result, countries that control the processing of rare earth minerals have a lot of political leverage. China processes most of the rare earth minerals used around the world, and it isn’t just consumer electronics that depend on Chinese exports. The US military’s F-35 fighter jets and Virginia-class submarines need rare earths too.

I spent years adjudicating war games for the US Navy. War games force players to identify the hidden constraints that render a beautiful plan untenable. Rare earth processing is exactly such a constraint. China showcased the power of its rare earths leverage with a series of export controls issued in 2025 that it agreed to suspend—at least until Nov. 10, 2026. Controlling the supply enables a government to slow a rival’s growth, or halt it. China's ability to extend the suspension of its export controls or let them go into effect gives it leverage on the geopolitical stage. In the parlance of Theodore Roosevelt, it's a very big stick.