4
To try and prevent another world war from breaking out
Attached is a link to a good World War 2 timeline that ranges from 1931 to the 1945 treaties.
LEND LEASE ACT
Because the Japanese violated all treaties and deserved it.
They had systems of interlocking mutual defence Treaties that the US didn't.
The original treaty to end the war with Germany was the Treaty of Versailles(28th June 1919) and for Austria-Hungary the Treaty of Saint-Germain-en-Laye(10th Sept. 1919).However, these treaties were not ratified by the US congress, so the US made separate treaties in 24th August 1921 with Austria and 25th August 1921 with Germany.
alot
405,400 US casualties are recorded for World War 2
Only one US submarine sank in World War One.
1,700 US Civilians were killed during World War 2.
Through war, treaties, and purchases.
international treaties