Self defense, the US was attacked.
1941
they were a allie.
How_did_the_us_involvment_in_World_War_2_escolate
The US supported the Cubans desire for Independence and the sinking of the USS Maine.
1945
Supplying Allies with weapons
The Japanesse surrender.
The US is not yet involved in world 11. The next world war should be WWIII so they have a way to go.
December 7th 1941
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.
World War I was from 1914 to 1918, US involvement was 1917 to 1918.