When it comes to 21st century weaponry, “hypersonic” seems to be the new buzzword. The United States is playing catch-up to Russia and China, whose militaries both have their own versions of hypersonic missiles.

Hypersonic means “faster than sound.” Russia became the first country to use hypersonic weapons in combat when it deployed at least 10 of them in Ukraine.

At the end of January, the Defense Advanced Research Projects Agency (DARPA) led a project with Lockheed Martin and the U.S. Air Force to successfully complete final testing on the Hypersonic Air-Breathing Weapon Concept (HAWC) missile. The missile was dropped from a B-52H Stratofortress bomber and reached speeds in excess of Mach 5 over the course of around 300 nautical miles.

Russia claims its Zircon hypersonic missile can travel at Mach 9, or nine times the speed of sound. Later this month, Russia will test launch another of its Zircon missiles off the coast of Africa. The launch is part of military exercises between Russia, China and South Africa. Putin calls the Zircon “unstoppable,” but as with many things Russian it’s a good idea to take that claim with a grain of salt.

As recently as 2021, Nikolai Yevmenov, the commander-in-chief of the Russian navy, said the weapon still had problems. A report from the U.S. Congressional Budget Office outlined some of the issues the U.S. found in developing the weapons, like how there still isn’t a good way to shield the electronics on hypersonic missiles from the sustained temperatures created at traveling Mach 5 or faster.

Another major drawback to hypersonic weapons is they are incredibly expensive to manufacture. An order of 300 ground-launched or sea-launched ballistic missiles cost $13.4 billion. The same number of hypersonic missiles would cost around 50% more, or $18 billion.

When it comes to powering hypersonic weapons, however, the Chinese may have just crossed a major milestone by creating a hypersonic generator.

The South China Morning Post reports a new peer reviewed paper published in the Chinese Journal of Theoretical and Applied Mechanics explains how Chinese researchers used magnetohydrodynamics generators to turn argon gas into an ion-filled plasma. The plasma was supercharged with electrical current. Using just .26 gallons of gas, the researchers produced an electric current up to 212 kilowatts.

The researchers say the new energy source could one day be used to power hypersonic missiles, lasers, even railguns. Conversely, it could also be used to help further fusion energy development, another somewhat fortuitous by-product of war industrialization.