Here is the latest on the whole deploying the THAAD missile defense system to South Korea that has the Chinese worked up:
The United States has included its advanced missile-defense system as part of the support it would provide South Korea in emergency situations on the Korean Peninsula, a South Korean military source said Sunday.
“The U.S. plans to deploy a Terminal High-Altitude Area Defense (THAAD) in case of an emergency on the Korean Peninsula,” a military source told Yonhap News Agency. “My understanding is that THAAD is easily transportable with a U.S. military aircraft.”
Washington has recently hinted at the deployment of a battery on Korean soil to better deter the North’s growing nuclear and missile threats. The U.S. stations about 28,500 troops in South Korea, a legacy of the 1950-53 Korean War, which is technically ongoing since no peace treaty has been signed to end it.
The issue of whether or not South Korea should host the American missile defense system has caused a bipartisan divide in local politics. While conservatives support the system, the liberal side has not been so welcoming since it believes the U.S. presence here undermines South Korean sovereignty. The U.S., meanwhile, claims the battery is defensive in nature. [Yonhap]
You can read more at the link, but it seems to me the ROK government is doing a good job of using this deployment as a way to pressure the Chinese to keep the North Koreans in line. If the North Koreans do something provocative the ROK can then tell the US to deploy THAAD to South Korea which is something the Chinese do not want. This keeps the pressure on the Chinese while simultaneously maintaining South Korea’s strategic goal of balancing its relationship with both China and the US.