there were plenty of howls about Vietnam, and if my number came...

there were plenty of howls about Vietnam, and if my number came up I had in mind to go to gaol rather than Vietnam

the answer to your question is in none of these wars did the US do it to take someone elses teritory for their own
for each of these wars the US had some reason ,which wasn't IMO always good enough reason ,but at least better than Putins .
In Iraq for instance a dictator who'd been murdering his people was removed
In Afghanistan they were chasing terrorists on their home turf and meanwhile trying to set up a stable government capable of keeping the peace there
Vietnam was the least easy to find a worthy reason for .

But why are we looking at the US .... if the US does something wrong does it somehow make what Russia is doing alright ?