The Sino-DPRK Treaty of Friendship, Cooperation, and Mutual Assistance, signed on July 11, 1961, turns 59 this year.

Since the treaty comes up for renewal every twenty years, this Saturday marks 365 days until Beijing and Pyongyang must reconfirm their military commitments to one another.

China’s superpower support — which has saved North Korea once before through its intervention in the Korean War — plays a crucial role in balancing against the U.S.’s regional alliances with Japan and South Korea.

Due to North Korea’s close proximity, the relationship is strategically valuable to China as well. Mao Zedong famously described the