Re: That is worrying...
"This is worrying on a couple of levels."
1: You assume China and Russia are friendly. They've been to war twice in the last century.
2: You're also assuming the chinese want to copy the aircraft rather than simply work out what's needed to take or keep them out of the air
3: Russia and the USA have "domestic" and "export" tech. Russia might have sold china a few Mig-35s but they won't be equipped with the same technology that the domestic versions get. In the same way USA export version F35s are inferior to domestic ones (and this extends downrange to things like F15/16s, the export versions are significantly less capable than the domestic units)