01.04.1612:02 AM ET

China Assembles Its Stealth Jet Fleet

Beijing’s newest supersonic warplane could mark the end of the American monopoly on stealth fighter jets.

China has apparently begun mass production of its new J-20 stealth fighter, making it only the second country in the world to produce radar-evading warplanes on a large scale.

But as with all military developments in China, it’s hard to separate fact from Communist Party-sponsored fiction—and equally difficult to predict just how heavily even large numbers of working J-20s could weigh on the military balance of power in the Pacific region.

The Chinese air force debuted the first prototype of the bulky, twin-engine, twin-tail J-20 in December 2010 at an airfield in southeast China belonging to the Chengdu Aerospace Corp., a state-owned airplane-maker.

Beijing’s test pilots got to work putting the new supersonic warplane—at 67 feet long, one of the biggest fighters in the world—through its paces, testing out its systems, flight characteristics and engines. (They’re either Russian-made AL-31s or Chinese WS-10s.) Over the next five years another seven copies of the J-20 joined the first example, each sporting small improvements over its predecessor. All J-20s feature the distinctive sharp angles of a plane designed to minimize its detectibility by enemy sensors.

The first eight J-20s were developmental, meant to support the gradual refinement of the new plane’s final design. But the ninth J-20, which government-run news outlet Xinhua revealed in a Dec. 29 story, is different. Signs point to this J-20 being the definitive version of the stealth fighter—and the first in what could be a long production run potentially numbering in the scores or even hundreds of planes.

To be clear, Xinhua was careful to imply, but not say outright, that the J-20 has entered full production. “The outside world would interpret it as the first mass-produced aircraft of the type J -20,” the news site stated.

And for good reason. For starters, the ninth J-20 sports all the small improvements of previous copies as well as a different numbering scheme than copies one through eight. The apparent prototypes bear four-digit numbers on their noses beginning with “20.” J-20 number-nine’s nose code begins with “21”—specifically, “2101.”

J-20 2101 also made its photographic debut in yellow primer paint, a kind of undercoat, instead of the black or silverish paint that the eight prototypes wear. Whereas Chengdu apparently picked the color scheme for the developmental planes, painting of the first production model—which could eventually join a frontline air force unit—“would need to be determined by the military,” Xinhua explained.

If indeed the ninth J-20 is the first production model, the next step for the Chinese stealth fighter is pretty clear. Plane number 2101 will join one of the Chinese air force’s regular fighter squadrons so that pilots and maintenance personnel can begin training on the type. More J-20s will roll out of the factory at Chengdu and join 2101 until there are enough production-model J-20s for a full squadron of a dozen planes.

When the squadron has enough planes and trained pilots and maintainers, the air force can declare the first J-20 unit “combat-ready”—a milestone most analysts expect sometime in 2017. At that time, China will join an exclusive club—as only the second country to field a fleet of frontline radar-evading jets. The American F-117, the world’s first stealth warplane, entered service with the U.S. Air Force in 1983. The U.S. B-2 stealth bomber followed in 1997, the supersonic F-22 stealth fighter in 2005, and the F-22’s smaller cousin the F-35 in July 2015.

By the 2030s, the Pentagon could possess as many as 1,700 F-35s plus 180 or so F-22s and 20 B-2s.

No other country has war-ready stealth warplanes, although Russia is working on one—and eight U.S. allies have ordered the F-35, with several more planning on also buying the plane in the near future. But while it’s pretty certain China will soon deploy J-20s, it’s not clear why—or how effectively—it will do so.

Beijing has never explained exactly what the J-20 is for. Is it a ground-attack plane like the F-117? A high- and fast-flying dogfighter like the F-22 or a multi-role attack plane and dogfighter like the F-35? And how does the J-20 fit into the Chinese government’s strategy for steadily exanding its sphere of influence into the East and South China Seas and the Indian Ocean?

Eying the J-20’s large size and sleek lines, some analysts have claimed that the J-20 is a kind of aerial assassin. Perhaps it’s meant to fly fast over long distances through U.S. and allied air defenses to fire missiles at airborne tankers, radar early-warning aircraft, and spy planes. Maybe it will lob bombs and rockets at air bases and aircraft carriers.

And Carlo Kopp, an analyst with the Air Power Australia think tank, wrote that he anticipates the J-20 “growing into the air combat role as more powerful engines become available.” In other words, becoming a close-in air-to-air dogfighter on par with the F-22.

Kopp’s qualifier is important. The production-model J-20 will apparently enter service with the same engines that power the prototypes. But the AL-31 or WS-10—it’s not clear which powerplant the J-20 uses—is clearly Beijing’s second choice for the new plane. Chinese engineers are working on the more powerful WS-15, which could give the J-20 more speed and maneuverability… if and when the new motor is ever ready.

Even if the ninth J-20 isn’t the first production copy, it at least represents another big step toward the production standard—and another impressive feat for the rapidly-improving Chinese air force.

But the most important milestone for China’s evolving stealth air force still lies somewhere in the future—its first time in combat. The U.S. Air Force has deployed radar-evading warplanes in all its major conflicts since the United States’ 1989 invasion of Panama. By contrast, China hasn’t fought a full-scale war since its abortive attack on Vietnam in 1979. Warplane development in a vacuum is one thing. But as Beijing’s own news service noted, “war is another matter.”