Re: Why is China being against the US-S.Korea joint military exercise? info
The PRC/PLAN is not in favor of any demonstration of might by the USN. It doesn't matter if it is the Taiwan Straits in particular or the Yellow Sea in general. I guess it would be the same thing if some nation (not on the best of terms with the US or not from the western hemisphere) held a naval exercise in the Gulf of Mexico / Caribbean Sea.
President Obama sending more SSBNs to the western Pacific armed with Tomahawk Missiles is also displeasing the PLAN.