In any case the fault lies with the US and not SK. But how can a terminal defense system be useless against NK missiles aimed at SK? The US could've used any excuse to build radars in SK. US can achieve the same with AEGIS destroyers docked in SK. If anything, US most likely intentionally choose a method that would drive a wedge between China and SK, so it would be foolish of China to allow the US to achieve that objective. And today with hundreds of ICMBs based far away from Northeast China and the capability to produce ICMBs like dumplings, THAAD is completely irrelevant. Even the most delusional policymakers in Washington cannot hope to survive a 2nd strike.