This article was written by Alex Hollings and originally published on Sandboxx.

After nearly two decades of counter-terror operations around the world, the United States military has recently begun shifting its focus away from this form of asymmetric warfare and back toward the potential for near-peer conflicts with nations like China or Russia.

Despite maintaining the most powerful military apparatus on the globe, this pivot won’t be without its challenges. Over the past 19 years, the United States military has funneled the majority of its funding into combat operations and new technologies that support the counter-terrorism endeavor. During this time, national opponents like China have had ample opportunity to observe the way America’s military operates, and find cost-effective methods of countering the U.S.’s most significant strengths.

In 2015, for instance, both China and Russia established space-specific branches of their armed forces tasked with replicating some of America’s orbital strengths (like a GPS satellite constellation), but also with finding ways to mitigate America’s established orbital dominance. Put simply, it’s cheaper and easier to interfere with or destroy technology than it is to replicate it, and America’s enemies have leveraged that simple logic to great effect in recent years. Today, it’s believed that both Russia and China operate semi-autonomous orbital assets that can already spy on or potentially even destroy satellites that are currently in orbit.

But while America has maintained the lead in orbital technology, it has apparently fallen behind in some weapons technologies that saw reduced focus throughout these many years of fighting terror organizations–namely, weapons technologies intended for use against technologically capable opponents. Hypersonics, as one pressing example, are a rapidly developing field of extremely fast (higher than Mach 5) weapons that, to date, no air defense system can counter. While both China and Russia claim to have operational hypersonic weapons in their arsenals, there’s one weapon that has wreaked more havoc in American military strategy than any other: China’s hypersonic DF-21D anti-ship missile.

Why is the DF-21D such a threat?

The DF-21D is a hypersonic anti-ship missile employed by China’s People’s Liberation Army (PLA). The platform itself is a medium-range, road-mobile ballistic missile. In fact, it’s the fastest anti-ship ballistic missile in service to any nation today. Once launched, the DF-21D follows a similar arc to that of an intercontinental ballistic missile, flying high into low earth orbit before deploying a hypersonic glide vehicle that can reach speeds as high as Mach 10 during its guided descent phase. Existing missile defense systems simply can’t intercept a target moving that fast, making it all but impossible to stop one of these missiles once it’s been fired.

The DF-21A TEL (Wikimedia.org).

While the DF-21D’s speed makes it a clear threat to U.S. Navy ships, it’s the missile’s range that poses the biggest problem. The DF-21D has an operational range of about 2,000 kilometers, or a bit more than 1,200 miles. By placing these platforms along the Chinese coastline, the PLA has been able to establish an area-denial strategy, sometimes referred to as an area-denial “bubble,” or a 1,200-mile circle around each missile that enemy ships can’t enter without being within range of the weapon system.

It’s important to note that, while these missiles can carry both conventional and nuclear payloads, the sheer kinetic force of a Mach 10 impact would be enough on its own to sink many ships, and when coupled with an explosive warhead, could conceivably take even a massive Nimitz-class supercarrier out of the fight with a single shot.