China contends that the system's radar would also cover Chinese territory. It protested Friday the announcement by close allies, South Korea and the US that they are ready to deploy the system, and summoned the U.S. Ambassador to China, Max Baucus.
State Department spokesman John Kirby said Friday the U.S. continues to need Chinese leadership and influence with respect to North Korea.
He told reporters that the system is "purely defensive" and was a response to the threat posed by North Korea to South Korea.