A Chinese military surveillance aircraft encroached on Japanese airspace Monday — the first known incursion of its kind — putting the Pacific further on edge. The breach comes a day before the US’ top security adviser is set to meet senior Chinese officials in Beijing, where he is expected to raise concerns about Taiwan as well as Beijing’s actions in the South China Sea. Japan has long sent fighter jets to intercept Chinese planes, and analysts believe the latest incursion is a message from...