Why the Asama Maru interception mattered

The incident caused a major controversy, yet Japan did not immediately enter the war. The action looked like a casus belli, although its status under international law was more complicated. The Royal Navy found the Japanese liner close to the home islands and removed 21 of about 30 German sailors aboard. The interception showed that British cruisers could locate a particular ship and seize selected passengers far across the Pacific. That same reach could threaten Japanese trade and therefore help deter conflict. In this interpretation, the episode also shows that the Second World War was global before the dates often used to define it that way.