The submarines attacked Pearl Harbor
It sank up to 2,779 ships in world war 2
The Germans then threatened to use only Uboats for war and blew up a few ships.
All countries fighting in World War 2 used weapons.
because of the alliances the US had made previous to the start of the war along with the threat of the German Uboats attacking US civilians and property.
germany
I definitely know that Canada was one of the Countries that did.
Germany
They all did.
I think it is because Germany wanted war.
Pretty much anyone involved in the war.
USSR