China is and has been for sometime the single greatest threat to world peace and security. To be fair, the other hemisphere will say the same about the United States. All things being equal, I'm more worried about China than anyone else.
The US is really good at distracting the public with jingoism and foreign enemies. We're really bad at cleaning up after ourselves, whether in war or at home (at least since WW2).
And if you don't think nation-state level actors have had those for a while now, to include the US, China, India, Iran, Israel, et al, then I have a bridge to sell you.