It was USSR before. It has been China since 1990's. An imaginary and powerful enemy has to be created. Iraq, Iran, Afganistan are too small for the title.
I agree that espionage is over-emphasized -- everyone does it. Also I agree that some like to imagine enemies; it fits their narratives. That doesn't make every enemy imaginary.
The USSR was a real enemy. Many Chinese leaders openly proclaim themselves our enemy and they take aggressive actions against us; among the public, aggressive nationalism is at least somewhat popular. Hopefully the relationship doesn't turn out that way, but it's a real risk that I don't think we should ignore.
[who?] [citation needed]
Try searching for 'kill a chicken to scare the monkeys'. A popular meme (at least popular enough that I've encountered it many times) is that China suffered a "century of humiliation" at the West's hands, that China is ascending and the U.S. is in decline, and now China will take what it wants as the great power of the world, including control of their region and territory from their neighbors (some of whom have security guarantees from the U.S.).
As far as actions, for example the Chinese military actively have harassed U.S. and allied nations' ships and planes, including causing a few serious collisions.
http://www.nytimes.com/2014/11/12/world/asia/china-turns-up-...