In February 2016, Chinese Foreign Minister Wang Yi expressed concerns that deployment of THAAD in South Korea, despite being directed at North Korea, could jeopardize China's "legitimate national security interests" and in 2017 the Vice Chairman of China's Central Military Commission asserted to the Chairman of the US Joint Chiefs of Staff that deployment of THAAD around China was one of the factors which had a negative influence on "bilateral military ties and mutual trust." The major controversy among Chinese officials is that they believe the purpose of the THAAD system, "which detects and intercepts incoming missiles at high altitudes, is actually to track missiles launched from China" not from North Korea. Chinese experts report that China is focused on the positioning of another THAAD radar system, this one on the Korean peninsula, for gleaning details about China's nuclear weapons delivery systems, such as THAAD's ability to distinguish which missiles might be carrying decoy warheads. Bruce W. Bennett pointed out that China has deployed an S-400 missile system to the Shandong peninsula, between Pyongyang and Beijing, which appears to be a defense against North Korean missiles.