The goal was to prevent Vietnam from becoming a communist state supported by the Soviet Union. Vietnam became a communist country: that's a clear cut Soviet win

The goal was to prevent Vietnam from becoming a communist state supported by the Soviet Union. Vietnam became a communist country: that's a clear cut Soviet win and US loss. That US was not able to translate its technical superiority in a victory is very interesting (including with regards to recent wars), but doesn't change the outcome. If you are talking about recent or ongoing wars (Afghanistan, Iraq, Libya or Syria), indeed the goals are much less clear, so it's hard to see how anything currently being done is really helping.