On Monday, the U.S. began the process of assembling an anti-missile system in South Korea, delivering the first of the five major components of the Terminal High Altitude Area Defense (THAAD) system. South Korea had requested an accelerated deployment of the missile defense system, approved last year, after North Korea launched four ballistic missiles on Monday, apparently in response to annual joint U.S.-South Korean military exercises. China "firmly opposes" the deployment, Chinese Foreign Ministry spokesman Geng Shuang reiterated on Tuesday. China will "take the necessary steps to safeguard our own security interests, and the consequences will be shouldered by the United States and South Korea," he added.
China fears the missile defense system will give the U.S. the capacity to detect Chinese missile launches, not just North Korean salvos, The New York Times reports. That would affect China's relationship with not just South Korea but also Japan and other U.S. allies in the region. President Trump spoke with the leaders of South Korea and Japan on Monday, assuring them that the U.S. will stand with its allies against North Korea. Geng warned the U.S. and South Korea to not "go further and further down the wrong road." The THAAD system will likely be ready by April.