PYONGYANG, June 10 -- The most consequential sentence spoken in Asia this week did not come from Washington, which was busy with its war in the Gulf and its quarrels at home. It came from Kim Jong Un, standing beside Xi Jinping in Pyongyang, declaring that the friendship with China is now North Korea's most important top-priority strategic work. Seven years after Xi last set foot in the country, the neighbor Pyongyang had drifted from came back, and was handed the front of the queue.

Xi's two-day state visit, his first foreign trip of the year, closed on Tuesday with the two leaders pledging closer strategic communication and broader exchanges across politics, economics and culture, Al Jazeera reported. The Korean Central News Agency car...