China conducts first test-flight of stealth plane

[Lamplighter]

People are very upset with Wikileaks for giving out secret US documents.

But I have wondered in the past, and now with this stealth plane being debuted in China,
just how do other countries make such rapid engineering progress.
I assume it has taken the US many years to develop the stealth designs and materials.
Did China really develop their designs independently of the US ?

We now know that Russia received documents for many years that kept them abreast of US weaponry.
But are these other countries (China, Iran, North Korea) likewise able to copy design developments ?
It would almost require them to penetrate each and every US company working on a project needed for a viable weapon.

I don't believe they are getting copies via Wikileaks.
Maybe I'm just paranoid enough to believe they are getting data
straight from the US government or from our allies.