Americans have expressed shock and alarm after a high-altitude balloon sent by China crossed U.S. and Canadian airspace, drawing criticism from the Pentagon. Secretary of State Antony Blinken canceled a high-stakes trip to Beijing in response. The balloon purportedly was a weather agent that had gone off course, though the Pentagon was skeptical. Whether or not the balloon was being used for meteorological intelligence-gathering, its presence above military sites is evidence of China’s disregard for U.S. sovereignty.

As Americans grapple with the implications of this incident, it is important to consider how it fits into a larger political war pattern. In many ways, flying a balloon over U.S. airspace is an indirect way to remind Americans of how their homeland is vulnerable to attack. In World War II, Japan launched thousands of balloon-borne explosives into the Pacific Ocean, with the aim of killing