This Friday, April 27, the South Korean and North Korean leaders will meet in the demilitarized zone dividing their estranged countries to discuss improving relations and possibly even formally ending the Korean War, which has continued in the form of an often tense and fragile armistice since the cessation of combat in 1953. This inter-Korean summit, the first since 2007, signifies closer ties between the two Koreas—and will be an important bellwether for Donald Trump’s late-May or early-June meeting with North Korean leader Kim Jong-un. It will also be watched closely by North Korea’s neighbor China, which has long stood as Pyongyang’s most important ally and played the role of gatekeeper for its relations with the rest of the world. While China’s Communist Party Secretary Xi Jinping’s meeting in March with Kim seemed to have fortified the recently-strained Beijing-Pyongyang relationship, it’s unclear whether Kim’s apparent diplomatic openings are to Beijing’s advantage.