You might mean why were the Americans so late in entering the war; if you're referring to WWII. The Japanese were probably the first enter WWII, if one were to count fighting in China in 1933. The US didn't enter WWII until the end of 1941 (December 7, 1941).
The U.S. wanted to remain neutral before World War 2. But after the attack by the Japanese on Pearl Harbor, America was not hesitant when entering the war.
so they can help out britain and not get taken over
I believe so
The US officially declared war on Germany in April 1917, thereby entering the war. It took a few months to get the military ready and ship it off to France, so by late 1917 and early 1918, the American Expeditionary Forces (AEF) were finally fighting in the war.
The Impact on the Japanese was that they lost trading privileges will the U.S.A, so that was extremely critical for the Japanese
In Article 9 of the Japanese constitution, it claims that the Japanese have renounced war. This constitution was written after World War II, and so although they have participated in wars in the past, such as the Russo-Japanese War or Sino-Japanese War, it does not mean that they are in war currently, or will be in a war in the future. If you are asking why Japan engages in war, the answer is the same as why any country would engage in war -- territorial expansion, imperialism, colonization, racism, etc.
Yes and No. The Japanese acquired Korea as a result the Russo-Japanese War, so the Japanese definitely fired shots in the war against the Russians. However, the Japanese did not fight the Koreans to occupy the peninsula.
Vast area, determined enemy.
The US was NOT at war prior to the attack.
The US entered when it declared war on Germany on April 6th 1917. So they entered late.
Do you mean, their version of the "Rebel Yell"? If so, it was "Banzai."
Usual reason(s). Underestimation of opponent.