Chinese Foreign Minister Wang Yi arrived in South Korea on Wednesday for his first visit in four years amid bilateral efforts to patch up relations damaged by Seoul’s decision to host a U.S. anti-missile system that Beijing perceives as a security threat. Wang’s visit came after years of tensions over the U.S. Terminal High Altitude Area Defense, or THAAD, system placed in southern South Korea and amid concerns that a U.S.-led diplomatic push to resolve a nuclear standoff with North Korea is beginning to fall apart. There’s also uneasiness over the U.S.-China trade war, which has hurt South Korea’s export-dependent economy and included U.S. demands that South Korean companies stop using equipment from Chinese technology giant Huawei based on security concerns.