North Korean leader Kim Jong Un made an unannounced visit to the Chinese border city of Dandong over the weekend to mark a key anniversary between the allies as Beijing and Pyongyang ramp up economic ties.

Kim was accompanied during his visit Saturday by Wang Huning, China’s No. 4 official, ?who passed on greetings from leader Xi Jinping, China’s official Xinhua News Agency reported.

The one-day visit came a day ahead of Sunday’s anniversary of Chinese troops’ entry into the 1950-1953 Korean War on the side of North Korea.