Chinese lookalikes are big news these days. Last month, at the murder trial of Gu Kailai, the wife of purged Politburo member Bo Xilai, the Chinese web was abuzz with speculation that the person on the stand was not Gu at all, but a body double masquerading as the defendant. The woman in court, there's no denying, looked at best like a plump half-cousin of the Gu we knew.

This week, China produced another lookalike – only this time the resemblance was far more convincing. The name of China's new stealth fighter may have sounded unfamiliar (it's called the J-21 or the J-31, depending on your sources), but this was a plane we'd all seen many times before. It looks like an F-22 from some angles, and an F-35 from others; but there seemed to be no mistaking that this was essentially an American stealth fighter with Chinese paintwork.

China has, of course, been in trouble for intellectual property infringements before. We await Washington and Lockheed Martin's submission to the World Trade Organization with interest.

But of all the setbacks to have beset Lockheed's F-35 program, this has to be one of the most galling. Overpriced, overdue, and underperforming, the F-35 was already a plane under extreme political pressure. Earlier this month one of the U.S. Air Force generals in charge of the program made it sound as if the government and Lockheed's relationship had practically broken down over the stealth jet's persistent failings. Deputy Secretary of Defense Ashton Carter has echoed these concerns. Other influential voiceshave called simply for the thing to be scrapped before its ruins American defense.

Yet all these perfectly good reasons to sell the F-35 prototypes on eBay to plane enthusiasts have so far been trumped by the aircraft's one great quality: that it was the strongest competitor in a field of one. Because of this ace characteristic, a number of countries – besides the program partners – have already begun ordering the pricey and totally unproven jet. The South Koreans are currently thinking about buying it even though Lockheed has denied them the opportunity to fly one before making their decision. Chances are they'll sign up anyway.

Only now a knock-off F-35 appears to be coming to market. Strangely enough, the possibility now exists that the F-35 will have to compete for export sales with a Chinese copy of itself. It's hard to pin down the unit price of an F-35, but it's at least in the $200 million range (and possibly a lot more). Ten years from now, you'll be able to find one for much less than that at the Chinese fake market, especially if you know how to haggle.

In all seriousness there are real economic implications, given that the F-35 needs to secure export orders well into the 2030s and beyond in order to recoup some of its crazy costs. The security implications are also serious. What if the J-21/31 undercuts the F-35 in cost terms while matching it in capability terms? What if, as The Australian newspaper reckons, China has extracted the full F-35 blueprints from BAE Systems' computers? What if, armed with that knowledge, the Shenyang Aircraft Corporation succeeds where Lockheed has so far failed and builds a Fake-35 that actually works?

Speculation aside, the reality is that the F-35 program is presently slated to cost $395.7 billion. China has probably spent less than 0.1% of that developing the Fake-35. Ladies and gentlemen, you're looking at the biggest free ride in the history of national security.