To learn more about the "day that will live in infamy" (the attack on Pearl Harbor (December 7, 1945)), consult the next page-heading titled "Pearl Harbor."
It is important to note that while this attack was the epitome of an attempted Japanese imperialism toward the United States, it was not the only example of the urge of expansion. Had Japan not previously grown this militaristic value to the point of an attack on arguably the most powerful superpower of the world, the United States' involvement in WWII would most likely either not occurred, or the entrance would have been prolonged and less severe.
It is important to note that while this attack was the epitome of an attempted Japanese imperialism toward the United States, it was not the only example of the urge of expansion. Had Japan not previously grown this militaristic value to the point of an attack on arguably the most powerful superpower of the world, the United States' involvement in WWII would most likely either not occurred, or the entrance would have been prolonged and less severe.
This clip provides an adequate explanation and illustration of the reasoning behind Japan's attempt at intimidation and expansion.