In all of the wars fought by the U.S. in its history, part of the plan was to send soldiers to certain death, if warranted to achieve a clear objective.
Take D-Day as the most striking example in modern times. Our commanders knew that we were attacking positions that were nearly impregnable. They knew that a significant percentage of our soldiers and sailor were going to perish in the attempt, and yet the generals did not hesitate (other than for the weather). 25% casualties was the expectation.
We took that same mentality into Korea and even to Vietnam. If an objective was militarily important, the commander would send troops in, even knowing that some percentage of them were going to die in the attempt.
That philosophy ended with the invasion of Iraq and is now dead. Compare the casualties from Vietnam - 50,000 killed, more or less - with Afghanistan, a war that lasted for about the same length of time, overall: less than 2,500 in ten years. Medical advancements surely had something to do with the dramatic difference in casualties, but the main driver in the reduced number of battlefield deaths was the change in military philosophy. NO commander in Iraq or Afghanistan ordered his troops into battles where casualties were a virtual certainty.
I attribute this dramatic change in battlefield philosophy to the advent of the all-volunteer army. NOBODY would volunteer, knowing that he might be thrust into a lethal battle on purpose.
Now look at what's going on in Ukraine. Those commanders, on both sides, employ the "old" military philosophy that an objective can outweigh the cost of a few lives. They send their troops into the occasional battle when they know some won't come out of it alive. Obviously, this is much more the case with the Russians, but also Ukraine.
What's my point? We are unprepared for a war right now. We have the weapons, the ammo, the technology, but our philosophy of fighting is incompatible with "winning" any war.
It is not my opinion that the draft must come back; it is a fact. There are many justifications for it, but this is the primary driver: We cannot rely on volunteers when the chances of getting killed or maimed goes above, say, 10%. NO ONE will volunteer. And recruiting is difficult enough now, due to the Biden/Obama wokeness initiatives.