It depends on how much is paid for what is won. And then it's a moral question of the value of a human life or the limits of pushing the bending of morality to the point it truly becomes immoral, and how far is just enough to still be moral. How many dead is too many? How many dead is still acceptable?
Were 60,000 Americans and hundreds of thousands of casualties of civilians, ARVN, VC and North Vietnamese soldiers worth it? I'd argue not, but the North Vietnamese would argue it (unfortunately) was. What if it were 1,000 American troop deaths and tens of thousands of civilian, ARVN, etc deaths? What is the status of that question if it won the US the war? What if it still lost, and the question became one of more soldiers could have won it, and if they won it, those dead would have not died in vain? What becomes the opinion if only 100 Americans died but hundreds of thousands of others still died?
War is an inherently immoral thing. But war is sometimes a necessary thing. It is the greatest contradiction of the human condition and material existence in the world. It is the great breeding ground of hypocrisy, but it is a hypocrisy that may need to be lived with if the war is just. When is it just? How do we find if it is just? And how do we live with the contradiction and the hypocrisy if we feel it is just? That is the question, and it is unfortunately absolutely relative. That is why the Vietnam War is such a complex psychology.