So, in WW2, the vast vast vast majority of the fight against "evil" was done by the USSR, because the Third Reich had, as one of its pillars, the destruction of the workers' movement and the enslavement of the Slavs. The USSR lost far more than any other party to the war because the Third Reich made the war of choice, dehumanized the Slavs, and engaged in genocidal mass murder as a choice. The USSR defeated 80% of the Third Reich's forces.
On the flip side, the American and British government and business communities were pro-fascist. They funded the rise of the Third Reich, they funded domestic and international eugenics programs, they were deeply invested in apartheid states and women's oppression. (By way of contrast, the Brits and Americans used women as prostitutes to support the war effort while the USSR had women all over their military as snipers, tank operators, pilots, machine gunners, etc.)
So given that context, let's look at the end of the war and what happened after. At the end of the war, the US wanted to make sure that the USSR didn't liberate the rest of Western Europe from the Third Reich because they were anti-communist. The USA led the Western allies to Germany to create a border with the USSR (also a member of the allies, remember). It was this insistence that divided Germany into East and West Germany. Berlin was in East Germany because the USSR was the predominant victor in the war.
But then what of Japan. Before the USA nuked Japan, the USA and Japan were negotiating terms of surrender. The USA had made a very strict and ultimately untenable set of terms. Japan replied that they needed some domestic face saving in order to prevent their country from descending into violent and bloody internal revolution immediately. The USA received that message, and then chose to nuke 2 civilian cities. There was no emergency. The US wasn't fighting for survival. Everything had already been secured. The USA was in active negotiations and Japan was participating (albeit through third parties because of the political sensitivity). The USA made an active deliberate choice to nuke civilians unnecessarily.
Why? Because communism was their real enemy. It was the reason they got involved in the war, it was the driving force behind their strategic decisions. They got involved against communism, they went to Germany against communism, they partitioned Germany against communism. And they nuked Japan as a show of force, or to demonstrate how bat shit they were, to create conditions of fear and restraint.
But if that were true, then wouldn't the USA have just launched a war against communism? They did. They launched wars of choice against Vietnam and Korea. They destroyed Cambodia. They bombed Laos. The most bombed countries in the world were bombed by the USA, with multiple countries having the USA drop more bombs on them than all bombs dropped by all parties in WW2 combined.
They continued their eugenics programs for 20 more years after WW2, they advanced their chemical weapons programs and deployed atrocity after atrocity in these wars of choice, mostly against civilians.
Are people in the USA used to wars of choice? Yes, because in essence all USA wars have been wars of choice, even before the USA existed. Was it a necessity to invade The Phillipines? How about Grenada? Overthrow the Iranian government? Afghanistan in the 80s? Was it an existential necessity to genocide the indigenous peoples of the Americas, poisoning their water, destroying their ecosystems, destroying their agriculture and their sources of food?
The entire Western European project, which became the North Atlantic project, is about wars of choice - brutal wars of choice of genocide through war, through rape, through collective punishment, through environmental devastation, through eugenics, through slavery, through death camps, through occupation and extraction. The number of necessary wars the USA has been in is so vanishingly small that the very few exceptions prove the rule.
