People in the know say that Chinese naval technology is roughly comparable to 1980s US Navy, but they are trying to close the gap. I've been told that even Japan in its weakened state can sink their navy.
However with America's military in decline I expect that in the next 10 to 15 years American security guarantees aren't going to be enough and Japan will defy the United States and re-arm.
Interesting that you say that. Not a doubt in my mind that the 1980s US Navy could annihilate the modern US Navy. Not even close.