Pearl Harbour.
No.
Germany
On Japan.
only on US
neutral
the us didn't declare war on china in world war 2 us declared war on japan on 1941 when japan bombed pearl harbor hawii
on decmber 8 1941
11th December 1941, shortly after German's declaration
Pearl Harbor is the event that made them declare war.
The United States was bombed by the Japanese at Pearl Harbor which cause a declaration of war but Germany had an alliance with Japan and it had forced the United States to declare war on Germany too. Then Germany had an alliance with Italy which cause the United States to declare war on yet another country. Then the world was at war and therefore World War 2 started.
no
In both.