BEIJING (AP) — Four decades after the U.S. established diplomatic ties with Communist China, the relationship between the two is at a turning point. Tensions have reached new heights on what has always been a rocky road, as the ambitions of a rising superpower increasingly clash with those of the established one. China ordered the closing of the U.S. Consulate in the southwestern city of Chengdu on Friday, in rapid retaliation for the closing of its consulate in Houston. Two weeks ago, Chinese Foreign Minister Wang Yi asked aloud if relations could stay on track. On Thursday, U.S. Secretary of State Mike Pompeo delivered an answer: The time has come to change course.