NYT reporters Perlez and Sang-Hun cite Prof. Shih of Renmin University in Beijing, about China's reluctance to take action against North Korea for missile testing by reducing oil exports and imports of mineral sources from North Korea. China sees stronger sanctions against North Korea, as urged by Japan, South Korea and the U.S., as being counterproductive by reducing Chinese influence in North Korea, alienating North Korea and further increasing its isolation. As a result China is maintaining improved relations with South Korea, as it continues to use diplomacy with the North Korean government. South Korea is responding to continued missile tests by North Korea in 2015-2016 by starting discussions for the deployment of a new Thaad missile defense system.