Lee Hae-chan, file photo.

A special envoy of South Korean President Moon Jae-in headed to China on the morning of May 18 for discussions about U.S. missile defense system THAAD and ways to contain North Korea, Yonhap News Agency reported.

The special envoy, Lee Hae-chan, will reportedly hand over a personal letter from Moon Jae-in, explaining the political compass of his new government.

Also high on the agenda of Lee's three-day visit will be discussions about a summit between the two countries' heads of state. The former South Korean prime minister is expected to meet with ranking Chinese officials, possibly including Chinese President Xi Jinping, Yonhap reported.

At a regular press conference on May 11, Foreign Ministry spokesperson Geng Shuang said Moon told Xi during a telephone conversation that Moon thinks highly of China's Belt and Road Initiative, and expects the initiative to bring development and prosperity to China, South Korea and other countries along the route.

Moon, who officially assumed office on May 10, has repeatedly criticized the previous administration under impeached leader Park Geun-hye for agreeing to host the THAAD system without seeking parliamentary approval, according to Korean news outlets.

In a May 17 report, Yonhap stated that Woo Won-shik, the floor leader of the ruling Democratic Party, said Seoul would consider uninstalling and returning the THAAD system to the United States. Woo also referenced the lack of parliamentary approval for this crucial national security decision.