Answer:
Prior to the beginning of the Second World War, the actions of Germany and Japan caused concern among their neighboring nations because they both engaged in aggressive expansionism. Germany, under the leadership of Adolf Hitler, began annexing territories in Europe, including Austria and Czechoslovakia, and also pursued a policy of militarization. Japan, meanwhile, embarked on a campaign of conquest in Asia, invading and occupying territories such as China and Korea. These actions created tension and fear among neighboring nations, who were concerned about the potential threat posed by these aggressive regimes.