Back when word came out that the F22 program was being cut,

and we're supposed to be all happy and unworried because A: nobody else had a 5th-generation fighter, B: the F35 JSF will take up the slack and C: there weren't any threats on the horizon that would demand the capabilities of the F22, I'd mentioned the fact that Russia was testing a 5th-Gen fighter and planning to sell it, and the PRC was working on a 5th-Gen also didn't exactly cause A, B and C to be comforting. "Don't worry about it, the Russians are a long ways from fielding it, and we don't think the PRC can put one in the air anytime soon", etc. Here's one of the reasons I think those excuses are bullshit:
A decade ago, China began introducing the HQ-9. Over a decade of development was believed to have benefitted from data stolen from similar American and Russian systems. The HQ-9 is deployed in ships as well. The radar apparently derived much technology from that used in the Russian S-300 system. ...Russia and the United States are debating how to deal with the growing Chinese use of stolen technology, especially for weapons systems that are exported and compete against the systems they are copied from. No one has a solution, and China denies all accusations.
Clinton, the bastard, let the PRC have a lot of tech, and they were then and still are stealing everything they can. Which means that, while they're probably a fair ways behind us on this, we can't count on it.

I remember reading, after the Soviet Union collapsed and a lot of information got out, that they had developed a heat-seeking air-to-air missile that was far more advanced than we'd had any idea of; happily, our guys hadn't had to face it in combat. Who says the PRC can't steal a march and supply stuff to someone just to give us problems? Who says they wouldn't?