I have a piece up at Asia Times Online...only at Asia Times Online! on the ROK's discussions with the United States over the THAAD missile defense system.
Here's the link.
Long story short, THAAD is ludicrous as missile defense for South Korea against the DPRK. It's the US government's way of getting anti-missile assets closer to the PRC. Understandably, the PRC is unhappy and has openly objected to the South Korean government.
IMO the main reason South Korea is considering THAAD is to vigorously yank the PRC's chain to "do something" about the DPRK and take the heat off President Park.
Please read and enjoy!