The US did enter into an undeclared shooting war with Germany in the fall of 1941 because Germany has declared war on the US.
US Congress declared war on Germany on 6th April 1917
sinking of lusitania
Germany's return to unrestricted submarine warfare.
Japan, Dec 7, 1941 (state of war existed); Dec 8, 1941 US declaration of war against Japan; Germany declared war on US December 11, 1941.
Zimmermann Telegram
Zimmermann Telegram
We entered the war in 1941 after the attack on Pearl Harbor. And then after we declared war on Japan, Germany and Italy declared war on us, officially starting WWII.
The US entered when it declared war on Germany on April 6th 1917. So they entered late.
Germany's unrestricted submarine warfare
it entered the war because Japan declared war (and attacked) it and Germany declared war on it, this was about six months after the start of the Holocaust.
Germany's unrestricted submarine warfare