world war 2 is the most tragic event in history, causing a lot of causalities and for hums to suffer at the hands of their irrational thinking leaders.
so far for USA it was the time to step aside its isolationism policy and face the curse which European countries have brought upon themselves. USA emerged as an angle to save the war devastated countries helped them rebuild under the Marshall Plan.
USA became the challenger to USSR.
effort to make UN for Peace and Stability in the globe.
USA shift of policy of war was seen as the effective mean to enhance the economy and defeat your enemy.
and making friend with enemy of the enemy.