First, North Korea's hydrogen bomb test made South Korea feel a greater threat. Earlier, South Korean President park geun-hye tried to unite with China to pressure North Korea to give up its nuclear weapons or exercise restraint. However, North Korea's hydrogen bomb test shattered this strategic goal of South Korea, and South Korea's influence on China and its attitude towards North Korea were very disappointed. South Korea has made up its mind to deploy Sadr.

Second, South Korea has been facing nuclear and missile threats from North Korea and has been considering how to safeguard its own security interests. At first, considering China's factors, South Korea held a clear opposition to the deployment of Sadr. With the change of the situation, South Korea's attitude towards Sadr has also changed, and the feasibility of Sadr has been gradually studied. North Korea's hydrogen bomb test played an important catalytic role in South Korea's deployment of Sadr.

Third, demonstrations against the domestic policies of President park geun-hye's government broke out in South Korea, North Korea conducted a nuclear test, and the Korean people put pressure on the government. If the park geun-hye government does not take necessary measures, it will face the risk of collapse.

Fourth, the United States holds the wartime command of the South Korean army. The U.S. military and government have always advocated the deployment of the Sadr system on the Korean peninsula, putting circuitous pressure on South Korea.

Fifth, South Korea's worries about China's economy. Although China is Korea's most important trading partner. In the fourth quarter of 20 15, South Korea's trade with China reached US$ 75.6 billion, surpassing Japan's (US$ 7 17 billion) for the first time and becoming China's second largest trading partner after the United States. However, it is an indisputable fact that China's economy continues to decline. If China imposes economic sanctions on South Korea, it will be a blow to the country's economy, so it is judged that China will not impose economic sanctions on South Korea.

Sade is an anti-missile missile that intercepts missiles. At present, the nuclear carrier is a missile. If there is a war between China and the United States, China's nuclear bomb will be intercepted and exploded there. On the other hand, the United States will hit its destination unimpeded. The greater use of Sadr in peacetime is that its reconnaissance range is larger than the missile interception range. The radar reconnaissance scope is deployed in South Korea, including most military movements in the northeast of China and the Russian Far East. Because your neighbor installed a monitor in your home, you can see what you do at home every day. Now, without a fight, the Saad system cannot be removed. Therefore, South Korea's deployment of Sadr is like a fishbone stuck in its throat, which makes China feel very uncomfortable.