I don't disagree that the US spent a vast amount on the Vietnam War and a lot of that was necessarily spent on propping up the South Vietnamese - but I think we're arguing past each other. Of course one expects the US to spend vast sums in a war its soldiers directly participate in. But the amount of aid given to Ukraine - as a pure proxy - is unprecedented. Did the USA hand over equipment worth more than the entire annual military budget of the USSR to the Afghan mujahadeen ? Or even to the South Vietnamese in the early days of the war when they were still officially just advisers ? Of course not, not even close - but it's not too much of an exaggeration to say that that's the situation we're seeing in Ukraine.