Do you think President Roosevelt was right to take the nation to war against Japan?
In the light of international law, it was a legitimate fight.
As the USA had been attacked by Japan, the war againt it was legal according to international law.
Japan and America were in diplomatic negotiations to curtail Japan's aggression in China. America was threatening to cut off all steel and oil imports to Japan. Japan had two choices give up its territorial ambitions or go to war with the United States.
Japan attacked Pearl Harbor before declaring war on the United States. The Japanese attack on Pearl Harbor was a clear violation of international law and gave the United States the legal right to declare war on Japan.
This surprise attack caused outrage in America. The Leadership 0f America were under political pressure to declare war. Basically the decision was made by the American people.
Also the surprise attack made it clear the Japan was at war with the United States. The Japanese followed up on the attack at Pearl Harbor with an invasion of Philippines destroying the American forces and the allied Phillipinese army on the islands. The conquest of Malaysia and attacks on other British territories made it clear that Japan intended to take over the Pacific.
As Japan was a war with the United States, the United States had no choice but to be at war with Japan.