The real purpose behind China's mysterious J-20 combat jet

The US Marine Corps did not mince words when deploying F-35s to Japan, saying that the "arrival of the F-35B embodies our commitment to the defense of Japan and the regional-security of the Pacific."

Tensions between the US, US allies, and China have been steadily mounting for years as China builds artificial islands and outfits them with radar outposts and missile launchers in the South China Sea, home to a shipping corridor that sees $5 trillion in trade annually.

One area where the US and China have indirectly competed has been in combat aviation.

In November, China debuted the Chengdu J-20, a large, stealthy jet that some have compared to the F-22 Raptor. But, according to experts, the J-20 is not a fighter, not a dogfighter, not stealthy, and not at all like the F-22 or F-35.

Dr. Malcolm Davis, senior analyst at Australia Strategic Policy Institute, told Business Insider that the "J-20 is [a] fundamentally different sort of aircraft than the F-35."

Davis characterized the J-20 as "high speed, long range, not quite as stealthy (as US fifth-gen aircraft), but they clearly don't see that as important." According to Davis, the J-20 is "not a fighter but an interceptor and a strike aircraft," that doesn't seek to contend with US jets in air-to-air battles.

Instead, "The Chinese are recognizing they can attack critical airborne support systems like AWACS (airborne early warning and control systems) and refueling planes so they can't do their job," said Davis. "If you can force the tankers back, then the F-35s and other platforms aren't sufficient because they can't reach their target."

Retired US Air Force Lt. Gen. David Deptula gave a similar assessment of the J-20 to Defense & Aerospace Report in November.

"The J-20 in particular is different than the F-22 in the context that, if you take a look and analyze the design, it may have some significant low-observable capabilities on the front end, but not all aspects - nor is it built as a dogfighter," said Deptula."But quite frankly, the biggest concern is its design to carry long-range weapons."

What the J-20 lacks in stealth and dogfighting ability, it makes up for by focusing on a single, comparatively soft type of target. Unlike the US, which has fielded extremely stealthy aircraft, China lacks the experience to create a plane that baffles radars from all angles.

Instead, the J-20's design makes for a plane that's somewhat stealthy from the front angle, as it uses its long range and long-range missiles to fly far out and hit tankers and radar planes that support platforms like the F-35 or F-22.

"They're moving into an era where they're designing aircraft not just as an evolution of what they used to have, but they're going into a new space," said Deptula of China's J-20 concept.

However, the J-20 may still be a long way off.

In November, Justin Bronk, a research fellow specializing in combat airpower at the Royal United Services Institute, told Business Insider that the models displayed at Airshow China were not much more than showpieces: "It's possible that the aircraft that were shown are still instrumented production aircraft," or planes with "loads of sensors to monitor performance" instead of in a combat-ready formation.

Former F-35 and F-22 pilot Lt. Col. David Berke also questioned China's progress in an interview with Business Insider, saying "it's really, really, really hard to make an effective nose-to-tail platform in the fifth gen."

Far from feeling threatened by the J-20, Berke seemed vindicated that the US's potential adversaries have worked so hard to counter emerging US capabilities like the F-35.

"If the things we were doing [with the F-35, F-22] weren't relevant, effective, the competition wouldn't be worried about trying to match it," said Berke.