China very nearly didn't go into the Korean war, and was betting on getting support from the Soviets when they did. Furthermore, the US wasn't under direct thre

China very nearly didn't go into the Korean war, and was betting on getting support from the Soviets when they did. Furthermore, the US wasn't under direct threat in the Korean war and was war weary from WW2. A new Korean war would likely have a more invested US, no outside help (except potentially on the US side), and a China with worse relations with NK. In addition, the primary fear for the CCP was that the US would try to march all the way to Beijing. There's no way that would happen today, so China has much less to fear from a modern Korean War than it did in the first.