China's strange response of missile defense system for South Korea

BBC:

The US and South Korea have agreed to deploy a controversial missile defence system, in the wake of intensifying threats from North Korea.

The Terminal High Altitude Area Defense (THAAD) anti-missile system will be deployed solely to counter the threat from Pyongyang, a statement said.

It is unclear exactly where it will be sited and who will have final control.

China, which has consistently opposed the plan, lodged a protest with the US and South Korean envoys.

China's foreign ministry said that the THAAD system will harm peace and stability in the region, despite its ability to detect and shoot down North Korean missiles.

"China expresses strong dissatisfaction and resolute objection to this", it said in a statement on its website.
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The BBC's Korea Correspondent Stephen Evans says that Beijing fears the system's radars would be able to see far into its territory. China, the North's closest ally, supported the most recent UN sanctions after North Korean nuclear and missile tests.
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If China was really concerned about the likelihood of the radar picking up threats from China too there are better ways to handle that than leaving the South defenseless to Nork aggression.   Also, think about what China is saying.  It wants to be able to threaten South Korea too, without being spotted by the radar signal.