The Americans chose a master of logistics (Eisenhower) as the supreme commander in Europe, and indeed delayed invasion by a year to minimize casualties and retain control of territory once conquered. That it caused more privation for the Russians was considered a convenient side effect, not a primary aspect.

The US was hardly hurt by the war at all, suffering comparatively few casualties; as their states were never actually attacked their primary contribution in Europe was to ship material from their factories to Russia and the other allies. Factories which after the war switched back to making commercial goods.

The war in the Pacific was a different matter, but again, only some US colonies were attacked and civilian suffering even in those territories was nothing compared to what other countries had to deal with.