Was WWII started because of the desire for world domination?Why did the Japanese bomb Pearl Harbor?

World War II happened primarily because of aggressive
actions of Hitler. And Hitler had expressed from time to time his desire and his promise
to German people to dominate the world. For example in his autobiography Mein
Kampf, published in two volumes in 1925 and 1927, he
stated his plans to conquer much of Europe. He promised to recover territories lost in
World War I and to add  Austria and parts of Czechoslovakia where Germans lived to
Germany. He also spoke of  seizing living space from Poland, the Soviet Union, and other
countries to the east.

Other indications of Hitlers desire
of dominating the world are his claim of racial superiority of German people, naming
Germany Third Reich.

Hitlers words were very much matched
by his actions. He started his expansionist program much before start of World War II.
He undertook vigorous program to increase the military strength of Germany from 1933
onward. In 1936, Hitler sent troops into the Rhineland, Hitler troops invaded Austria in
1938 and made it a of Germany. Then he secured consent of France and Great Britain
consented to occupation of the German-speaking areas of Czechoslovakia. He took control
of the rest of Czechoslovakia also in March 1939.

Hitler
wanted to take over Poland also, but Britain and France took action to guaranteed
Poland's independence. In August 1939, Germany and the Soviet Union signed treaties of
friendship which among other things divided Poland between Germany and the Soviet Union
and promised the Soviet Union other territory in eastern Europe. This was clearly an
attempt by Hitler to take support of Soviet Russia against France and Great Britain,
before launching a major offensive against them.

From all
these facts it is very clear that Hitler's desire for world domination was a major cause
of starting and extending World War II.