Symbolic - US has a dozen of those... expect China to step up competition as her economy balloons. It will be a while though, US is the biggest military spender by far. I find it moronic that the Chinese won't deal firmly with North Korea while whining about US missile and fleet deployments in the region.
You should read the Korean War history to understand why.
China uses Korea as a proxy. China is wary of Seoul and has believed for years that the US has stationed nuclear weapons in Seoul. There is a huge military presence - and multiple bases. China - a participant in the war - considers them hostile advance forces.
The kind of military exercises Seoul conducts with the US are tuned to a scenario in which China is the enemy. The anti missile radar being installed in South Korea has a wide span covering most if not all of China.
The Russians too are jittery about the American activities.
Note that China "inherited" North Korea from the USSR. It is believed that they encouraged Kim Il Sung to go nuclear to bring sense into a triumphalist America and he did.
The problem for the Americans is that any war on Korean peninsula would destroy the two Koreas and Japan. I believe all the participants in the Korean war of the 50s would rejoin.