Why did roosevelt support a "european first" strategy even though it had been japan that had first attacked the united states?

Roosevelt supported a "European First" strategy, for they believed that in taking out the more powerful power (Nazi Germany), and helping their allies achieve victory would be better, as most of their resources could be focused on defeating the stronger power. They first eliminated the Fascist government in Italy before defeating Nazi Germany, and then turning their attention to Imperialist Japan. This way, they would not only be able to take out the stronger powers, but also to free up their allies to help attack Japan.

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answer; /// i believe that the correct answer is( it left behind rich