The bombing of Pearl Harbor was the reason. Roosevelt made an announcement that the Japanese bombed us and we are going to war.
Sources:
my 8th grade textbook
Finland repaid its war debt to the US.
Germany
Germany
The US .
Finland
Japan
Germany
The main act was the attack on Pearl Harbor.
The Japanese bombed Pearl Harbor on December 7, 1941
The Zimmerman telegram
The emergence of a powerful Soviet Union
Finland repaid its war debt to the US.
Italy
The bombing of Pearl Harbor by the Japanese on December 7, 1941.
Finland repaid its war debt to the US.
To get a peace from all country during world war 1
The debts of World War I shifted the world's financial center from England to the US.