Answer:
The U.S joined the military combat in WWII after the attack on pearl harbor.
On 7 December 1941, while German armies were freezing before Moscow, Japan suddenly pushed the United States into the struggle by attacking the American naval base at Pearl Harbor, Hawaii. Four days later Hitler declared war on the United States.
And what did hitler do to cause the war?
Hitler smashed the nation's democratic institutions and transformed Germany into a war state intent on conquering Europe for the benefit of the so-called Aryan race. His invasion of Poland on September 1, 1939, triggered the European phase of World War II
Step-by-step explanation: