On a night apparently in early September, at a flight test center somewhere in China, a dark-painted airplane reportedly took off on a momentous mission—to fly faster than five times the speed of sound, then return safely to Earth.

The airborne experiment, allegedly involving a manned aircraft with a human pilot aboard, marked a huge leap forward for China as it competes with the United States to develop warplanes and missiles capable of so-called “hypersonic” flight—so fast that they’re almost impossible to shoot down or dodge.

Yes, the September test was a massive technological step. But only if ... it actually happened. For as suddenly and dramatically as the news of the aerial trial broke, it quickly evaporated. Now it’s not clear what, if anything, actually occurred in the sky over that Chinese airfield.

Reporter Qi Shengjun from China Aviation News is, so far, the sole source for the potentially world-changing development, one that could give Beijing an enormous military edge over Washington. In a dispatch dated September 18, Qi breathlessly described the nighttime test—the "roar of the engine," the dark-painted aircraft as it “disappeared in the sky,” the “excitement” and “indescribable emotion” of the test team on the ground.

“A few hours after takeoff, the task is complete,” Qi wrote, adding a literary fluorish as he compared the test plane’s landing to the sheathing of a sword. “When the ‘aircraft brake’ instruction is issued, this mission comes to a successful conclusion. The original anxiety and tension is instantly released—applause, laughter sounding in the control room.”

“The flight test center achieved a breakthrough in the field of hypersonic flight.”

But Qi’s news report appeared only briefly at the state-run website of China Aviation News. A few days later, the story was gone—either retracted or censored.

The Chinese Communist Party keeps a close eye on the country’s media and routinely suppresses stories it's not comfortable with. An army of censors working for the Public Security Bureau scours news sites and blogs and other social media sites, yanking any material considered politically sensitive. The censors pay close attention to any Web content describing Chinese military capabilities.

Now, at any other time the Party might have been happy to celebrate yet another breakthrough in China’s rapidly developing high-tech weapons industry. But mid-September marked Chinese President Xi Jinping’s first official visit to the United States.

In talks with President Barack Obama, Xi struck a conciliatory tone—vowing to crack down on cybercrime, for instance, and also proposing to team up with the U.S. government to shut down the illegal ivory trade that’s driving the slaughter of an estimated 30,000 elephants every year.

Maybe September wasn’t the best time to shove a new hypersonic aircraft test in America’s face. Maybe Qi’s report was overeager; hypersonic engineering is a notoriously difficult-to-master discipline.

Whatever the reason, Qi’s dispatch disappeared. But that shouldn't necessarily cast doubt on the underlying premise of his reporting. For years now—decades, even—China and the United States have been making uneven progress toward the very kind of high-tech achievement Qi described.

Hypersonic aircraft are not new. In October 1967, the X-15 rocket plane—the product of collaboration between the U.S. Air Force and NASA—achieved Mach 6.7 with pilot William Knight at the controls. That speed record for a manned aircraft still stands.

More recently, the Pentagon has been tinkering with a number of unmanned hypersonic missiles and gliders that it hopes to turn into weapons someday. But it’s no easy task to design a vehicle that can travel faster than Mach 5 reliably and safely while also being affordable.

Around half of recent U.S. hypersonic tests have ended in failure. More than 40 years after the X-15’s first flight, the Pentagon is still struggling to deploy a hypersonic aircraft it can use in day-to-day operations.

Undaunted, in 2013 Lockheed Martin proposed to build a Mach-6 spy plane for the Air Force. “Speed is the next aviation advancement to counter emerging threats in the next several decades,” Brad Leland, Lockheed Martin’s hypersonics program manager, said in a company press release.

Not to be outdone, Boeing is working on a prototype drone space plane for the military’s fringe-science Defense Advanced Research Projects Agency. The company hopes the XS-1 will reach speeds up to Mach 10, allowing the robotic plane to boost small rockets into low orbit starting as early as 2019.

While America doggedly pursued high-speed aircraft, China raced to catch up. A few years ago, Beijing built the world’s largest wind tunnel capable of simulating conditions up to Mach 9. In 2012, China Aerospace Science and Technology Corporation tested a new rocket-style, solid-fuel engine for hypersonic flights. Two years later, Chinese engineers began a series of tests of a Mach-10 glider called the WU-14 that could form the basis of a new missile or drone.

The new research warranted a mention in the 2015 edition of the Pentagon’s annual report on the Chinese military. Beijing “is developing and testing several new classes and variants of offensive missiles, including hypersonic glide vehicles,” the report warned.

But if Qi’s reporting is accurate—if a manned hypersonic plane just completed a successful first flight—and if that plane someday proves suitable for routine use, then China would no longer be just trying to catch up to the United States when it comes to flying Mach 5 or faster.

Indeed, China might have zoomed right past America, potentially taking the lead in super-speedy airplanes.