Conversation so far:
who was the president during pearl harbor attack
Franklin D. Roosevelt was the US President during the pearl harbor attack.
what year was the attack on pearl harbor
The attack on pearl harbor occurred December 7, 1941.
how did the attack on pearl harbor affect history
One further consequence of the attack on Pearl Harbor and its aftermath was that Japanese-American residents and citizens were relocated to nearby Japanese-American internment camps.

Question: why did the attack happen
Self-contained rewrite: why did the attack on pearl harbor happen