GP's actually true that the nukes wasn't the decisive factor but the Soviet invasion was. The popular narrative that American nukes ended it is merely the most useful version.

The bomb was not a principal contributing factor. We're talking about fascist ideologues hellbent on every man, woman and child dying to stall an invasion of their homeland. Of course the thing they feared most weren't new types of bombs, which did not change their situation. The thing the feared most were those horrible communists.

Defense of Taiwan is very important for the sort od reasons you're talking about. The defense of Israel though? That's a net negative which causes America a great deal of reputational harm around the world. With regard to Europe taking their own defense industry seriously again, I think that is ultimately a good thing for the American public, and in any case isn't caused by the trend of younger Americans disliking Israel. Rather, it is caused particularly by a certain baby boomer presidential candidate who simultaneously suggests that America shouldn't oppose Putin invading Europe AND that America should instead triple down on support for Israel.

As for people going "further right" as they get older, the younger American generations disliking Israel isn't a right/left thing. Young right and young left both dislike Israel, for their own reasons. Churches in America, particularly white evangelical churches from whom support for Israel is the strongest, are in a precipitous decline. They look like nursing homes now, younger generations aren't coming back and the boomers in those churches are in a panic over it.