Why did having Soviet Union as an ally contradict one of the reasons for the United States involvement in the war?

As Allies, if one country were to attack your ally and your ally request your help to battle them your country must or it will break the promise and treaty they signed so they can be allies but Pearl Harbor was the best reason and main reason the U.S join the Allies in WW2

the civil war was a fulfillment and completion of the constitution, not a revolution against it. changes in culture and society surely affected political life. lincoln hoped to bring the north and south together after the war by healing the nationand making people lose their resentment.

hope this you out just took thus test a min go and mad a 100

it increase by 12% a year from 1812-1820