During WWII.
During Vietnam people HATED the war. People hate this current war as well, but not so much. These days, people are less easily sucked in by war propoganda. War is unpopular.
Everyone thought that WWI was going to be a picnic. In a new major war, many Americans would question the purpose of the war. If they hated it enough, then they would elect someone else during the election.
The American people question their government more then say, Russia. They may support the war initially, but they would likely protest as the war draws out. This applies to the West in general though.
We may win the war but there is no wa ywe would even attempt and occupation.
There's been a lot of posts in this thread that annoyed me - mostly because much like Liberty Prime, I consider Communism the very definition of failure. But even deliberate trolling attempts fail to annoy me as much as the complete ignorance of
the belief in the status quo.
Public opinion is fickle to the extremes. Over the course of just 10 short years, public climate can change completely and people just forget or ignore whatever position they held yesteryear. There's nothing specificly preventing the U.S. population from becoming even more of drooling sheeple than they already are.
"Why of course the people don't want war. Why should some poor slob on
a farm want to risk his life in a war when the best he can get out of
it is to come back to his farm in one piece? Naturally the common people
don't want war neither in Russia, nor in England, nor for that matter in
Germany. That is understood. But, after all, it is the leaders of the
country who determine the policy and it is always a simple matter to
drag the people along, whether it is a democracy, or a fascist
dictatorship, or a parliament, or a communist dictatorship. Voice or no
voice, the people can always be brought to the bidding of the leaders.
That is easy. All you have to do is tell them they are being attacked,
and denounce the peacemakers for lack of patriotism and exposing the
country to danger. It works the same in any country."
Public opinion or socio-political 'waves' is no linear development or actual science. You can't compare any future war to that of the Vietnam war just because it was later than WW1. Especially if there's a direct threat to the nation people identifies with and especially if, as a change of pace, the other nation is the immediate aggressor.
If there's a direct threat to organized resistance of the U.S. on American soil, it's the real or percieved complete balkanization of your nation.
Not saying that it wouldn't be interesting to see actual warfare carried out in modern urban areas.
Edit: Not that I'd call China a 'good' communist state. I actually kinda like them. But don't tell anyone.