The current stance of China on the deployment of THAAD in South Korea is indisputable. China opposes to North Korea’s possession of nuclear weapons and is suggesting six-party nuclear talks (the US, China, South Korea, Japan, Russia, North Korea) as the solution, favoring “conversation over constriction.” Therefore, China relentlessly disagrees with the deployment of THAAD, asking for the US and South Korea to respect China’s “strategic safety profit”.
After the summit meeting between President Park Geun-hye  and President Xi Jinping in Hangzhou on Sep. 5, there was an interpretation that the opinion conflicts between South Korea and China had been alleviated. During the meeting, even though President Xi announced his opposition of the deployment of THAAD in South Korea, he claimed that amicable relationships must be retained between South Korea and China, mentioning 3 years of Korea Provisional Government in Hangzhou as an important connection, that South Korea and China can pursuit common gains.
Therefore, as North Korea launched the 5th nuclear test on Sep. 9, political experts and media in South Korea came to have somewhat of a ‘hope,’ that China would no longer ignore the global threat that North Korea holds through successful development of its own nuclear weapons. Criticizing North Korea’s violation of UN mandates, China summoned North Korea’s ambassador Ji Jae Ryong, and proclaimed that it would join in additional resolutions against North Korea. However, on the following day (Sep. 10), China Daily reported “The deployment of THAAD rather stimulated North Korea” as its top article. They also pointed out that ‘it is a default to agree on the deployment of THAAD in South Korea just because of North Korea’s 5th nuclear test. They must be dealt with separately.”
It is acknowledged by many experts that China holds the key to stop North Korea. Even at this moment, China stopping its supply of fundamental resources to North Korea such as oil can be extremely influential on North Korea’s next move. However, the current Chinese government run by President Xi is having enough problems with various internal tasks such as aiming for consecutive terms of President Xi and achieving certain percentage of yearly economic growth. Therefore, while the South China Sea disputes with the US continue, maintaining stable political relationships with neighboring countries at the minimum economic costs seems to be the primary political agenda of China.
China’s policies on Hanbando (the peninsula that includes North and South Korea) are another main reason for China’s stance on the deployment of THAAD. China’s Hanbando policies are based on two broad subjects: the maintenance of total stabilization in Hanbando and exercise China’s influence both on North and South Korea through the balance between them. As North Korea’s consecutive nuclear test and the deployment of THAAD in South Korea are intimidating China’s very root of policies on Hanbando, China becomes hesitant to join in the alliance of the US, South Korea and Japan, against North Korea. While the launching of nuclear weapons in North Korea must be stopped, which the alliance is willing to do so even at the expense of North Korea’s regime change, China cannot ignore the possible uncertainties and unbalance between North and South Korea as a corollary.
Since the G20 Summit in Hangzhou on Sep. 5, a ‘2nd Cold War’ has been developing between China and the US. As the South China Sea disputes are escalating, the formation of alliance between South Korea, the US and Japan is reluctantly provocative to China. Considering that North Korea is using discord between the alliance and China as an escaping exit for developing nuclear weapons, the cooperation of China is more important than anything else at this point.