Why was Japan's attack on Indochina upsetting to the US?

Answer 1

Now, I assume you mean why the Japanese were angry at the Americans during World War II? If so, it was because, at the turn of the 20th century, the Japanese faced rapid modernization and militarization. They had goals of conquering colonies to have a large empire like what the Western world was doing. Because Japan is an island nation, its resources are limited. Prior to WWII, the Japanese needed sufficient fuel for their warships, planes, and transportation, as well as oil and steel. To solve this problem, the Japanese wanted to attack the United States in order to acquire ample resources. This eventually led to the attack on Pearl Harbor and the U.S. entering WWII.

Answer 2

Because the Japanese did not like the product of what they sew.

Answer 3

indochina was on our side