China’s reported test of a new orbital weapon with nuclear capability is bad news for the United States.

But the test also is a rational response to decades of American provocations. And if those provocations don’t end, rivals such as China are sure to develop even more capable nukes.

There’s a term for this back-and-forth nuclear escalation. “Arms race.”

Financial Times journalists Demetri Sevastopulo and Kathrin Hille first reported the August test of the potential fractional orbital bombardment system, or FOBS.

As its name implies, a FOBS launches like a traditional intercontinental ballistic missile then enters a brief but stable orbit before de-orbiting after just a fraction of a trip around Earth.

Where a traditional ICBM only briefly escapes the atmosphere as it predictably arcs toward its target—over the North Pole, in the case of a Soviet or Chinese ICBM heading for the United States—a FOBS stays in orbit just long enough that, depending on its trajectory, it can streak toward a target from any of several directions.

As many of the most powerful strategic radars are fixed, and thus point in just one direction, a FOBS has great potential for an atomic sneak-attack. A FOBS also is more survivable than an ICBM is, as it can zoom toward its target along an axis where enemy anti-missile defenses are thinnest.

“China did this—and is doing a bunch of other things—because they want to be able to have a secure second-strike capability,” said Jeffrey Lewis, an arms-control expert at the Middlebury Institute of International Studies in California, “and when they look at our nuclear modernization and our missile-defenses, they have decided they need to increase the number of nuclear weapons they have and look at coming over the South Pole.”

In nuclear parlance, “second-strike capability” is the nukes a country would launch after an initial enemy atomic attack. Possessing a second-strike capability is critical to mutual deterrence. A potential nuclear aggressor must believe it can’t escape largely unscathed in the event it launches an atomic sneak attack. To be deterred, the aggressor must believe it’s going to suffer a devastating second strike.

It’s not hard to understand why Beijing is worried about its existing second-strike capability and thus is working on a new orbital nuke. The U.S. military since 2002 has spent hundreds of billions of dollars developing ever more sophisticated land- and sea-launched anti-missile missiles. The latest missile-defense systems might even be able to knock down lower and slower ICBMs.

The administration of President George W. Bush withdrew the United States from the 1972 Anti-Ballistic Missile Treaty and doubled down on missile-defense spending in order to develop weapons capable of stopping an Iranian or North Korean nuke. Successive administrations have continued the high level of missile-defense spending.

But the same missile-defenses, while overall unreliable, could threaten the effectiveness of Russian and Chinese missiles, too. And in so doing, the missile-defenses undermine the mutual deterrence that, since the 1950s, has prevented the world’s leading atomic powers from nuking each other into oblivion and, in the process, devastating the entire planet.

Chinese leaders correctly view American missile-defenses as an affront to deterrence. FOBS represents one effort to restore the mutual nuclear threat. “They’re not going to limits offensive systems unless we agree to limit missile-defense systems,” Lewis said.

But U.S. leaders—to say nothing of everyday Americans—probably aren’t willing to dismantle the sprawling missile-defense establishment.

Deterrence is all about accepting your own vulnerability in exchange for the enemy accepting his vulnerability. Each state counting on the other’s fear of nuclear destruction to prevent either from pressing the button and starting an atomic war.

But that carefully calculated mutual vulnerability to anathema to many Americans’ worldview. “It’s especially hard for Americans to accept we might have to live with some degree of vulnerability,” Lewis explained.

Instead of making peace with mutually assured nuclear destruction, Americans prefer to continue developing expensive, unreliable missile-defenses that might not work in the real world but at least signal strength and defiance. It’s a comforting delusion.

It’s for that reason that the U.S. political and defense establishments are likely to respond the wrong way to the Chinese FOBS test. The rational response is to appreciate Chinese fears regarding the erosion of mutual deterrence and take steps to restore that deterrence by dismantling the missile-defenses that threaten Beijing’s second-strike capability.

The irrational response—and the likely one—is to view the FOBS test as a senseless, ahistorical provocation that demands some new technological countermeasure. In other words, more and better missile defenses.

That response couldn’t be more absurd. America’s fixation on missile-defense is what got it into this pickle to begin with. Adding more missile-defenses in order to defeat FOBS probably will only encourage China to develop even better nukes. Which might then prompt the United States to deploy yet more anti-missile missiles. Et cetera, ad infinitum.

“People are going to use this to accelerate the arms race,” Lewis said. And there are no winners in an out-of-control arms race. “We all lose.”