The US began it's involvement in WW2 on December 8, 1941.The day after the attack on Pearl Harbor.
FDR declared that we are going to enter WW2 a day after the Pearl Harbor attack.
1941
they were a allie.
How_did_the_us_involvment_in_World_War_2_escolate
1945
Supplying Allies with weapons
The Japanesse surrender.
Self defense, the US was attacked.
December 7th 1941
Pearl Harbor
the japs bombed us
The US entered World War 2 after the attack on Pearl Harbor. When over 2,400 US lives were lost in a sneak attack on a Sunday morning, there was no stopping US involvement in the war.
From supplying the weapons of war to becoming the primary combatant.