Not much. The President of the United States at the time was already hostile towards Germany before the war started for whatever reasons, but put up a charade to the American public of wanting to remain neutral. In mid 1941 US ships were ordered to attack German U-boats on sight, even though president Rooseveldt was still promising the people of America that the US would remain neutral.
The delicate neutrality was eventually broken by the Japanese attack on the United States Navy at Pearl Harbour, after a great deal of American provocation. War against Japan was the covert strategy of President Rooseveldt for the US to enter into war against Germany with mass public support.
Whether a victorious Germany would have been an actual threat to the US can be debated until judgement day without resolve.
German U-boats sank US ships (WWII), this was enough provocation on its own. Sinking the Lucitania(sp?) got us into WWI.
germany
Belgium
The Germans were sinking its supply ships heading for France and England.
When the Japanese attacked the US.
belgium
Adolf Hitler
germany
gently
Germany. Germany caused Americans to be raged, and want President Woodrow Wilson to take action in the war, but he kept neutrality for a while, but then entered the war.
Belgium
BRITIAN WAS IGNORED. GERMANY IGNORED THEM.
The Soviet Union signed a neutrality pact with Germany in 1939. This divided much of Eastern Europe between the two countries.
the passage of the Neutrality Act of 1939
neutrality act
The Lend-Lease program was a note-worthy departure from neutrality because then US was openly supporting a known enemy of Germany and the Lend-Lease program later led to even more support to England and it's war with Nazi Germany .
The Germans were sinking its supply ships heading for France and England.
Submarine Warfare