It would be outright ludicrous for China to imagine that they could use North Korea to test advanced weaponry without anyone tracing it back to them.
He again acquired the technology in Europe when working for Urenco, a nuclear fuel company.
The whole Q.A Khan affair is quit a fascinating story actually.
Some more information on http://world.time.com/2011/07/07/a-q-khans-revelations-did-p... and https://en.m.wikipedia.org/wiki/Abdul_Qadeer_Khan
I did also see a very good documentary about this, but I can not find it online right now.
Edit: Here is the BBC documentary about Khans dealings in nuclear secrets: http://www.unewstv.com/6821/bbc-documentary-on-dr-abdul-qade... . Stranger then fiction, it has a plot like a top thriller movie.
More like when a D student marks their own test, scores 5% and announces they've passed.
I'm not sure if any other nuclear weapons state has had such a string of failures. Both the US and USSR had successful full yields for their tests of their first fission and fusion bombs. China's first fusion weapon test yielded over 3 megatons.
North Korea's test yielded probably under 10 kilotons, and they're going around bragging about an H-bomb. I'd say that deserves a D, at best.
And it's not North Korea either, as they're F- students. I still don't understand the big deal here, they fizzle-yielded their first two tests, and their claims of an H-bomb are ridiculous. They don't have the infrastructure, expertise, or materials to make Ulam-Tellers. This is bad propaganda from crackpot murderers.