South Korean President Moon Jae-in began his first state visit to China on Wednesday. The four-day trip aims, among other things, to soothe relations that became strained after the US deployed an anti-missile system on the peninsula, angering Beijing. Moon is also expected to discuss the North Korean nuclear crisis at talks with Chinese President Xi Jinping on Thursday. The US installed the Terminal High Altitude Area Defense (THAAD) system in the South earlier this year, to guard against threats from North Korea, and Beijing considers the deployment a threat to its own security.