China does not want the US building military bases a few miles south of their border. Additionally, in the event of a conflict with the US directly, the DPRK w

China does not want the US building military bases a few miles south of their border. Additionally, in the event of a conflict with the US directly, the DPRK will almost certainly seize the opportunity to cause havoc on the peninsula and therefore divert US/NATO resources away from a Chinese/US conflict. One could argue that the US wouldn't need to maintain bases on the peninsula after the fall of the DPRK, but with the situation in the South China Sea, we'd be stupid not to and even if we agreed with China that we wouldn't, they don't have a lot of reason to trust we'd hold up our end of the bargain given our history.