Just recently I had an "Aha! moment." Thanks to this article by Gary Barnett, I learned why the FedGov has been in Afghanistan for so long, and why it fought a war in Vietnam.
Perhaps you already saw the reason, and wonder why I'm such a latecomer. I've no defense. Perhaps we all have a blind spot or two, and this is one of mine. I'd vaguely supposed the Afghan one had something to do with oil (it lies between Iran and China) but that assumes the FedGov must control oil supplies in order for American refiners to buy any; clearly not true.
Rather, the reason is this: wars the US Government now fights are not intended to be won, or at least winning or losing is not the issue, provided of course any loss doesn't involve a loss of its territory (especially the District of Columbia.) That's the generality. In 1861, 1917 and 1941 I think it did set out to achieve victories, and succeeded; but while huge, those are only three out of at least 115 it has waged since 1783. Notice too what happened after the triumph of 1945: FedGov spending (and taxes) dropped like a rock, the Depression ended and decades of prosperity began (chart courtesy of the Tax Foundation.)
Wonderful news for everyone... except the weapons makers.
So a pretext was found to engage in the Korean war, and the "defense" industry regained its health; there was never any suggestion, even, that the bad guys in Pyongyang were planning an invasion of Oregon. Notice that 60+ years later, the Korean war has not ended. Soon afterwards came Vietnam, again without a shred of defensive need, and arms makers of all kinds enjoyed a bonanza. President Johnson himself is reported to have prospered well by investing in Bell Helicopter and other firms actively supplying arms to the conflict that he escalated. The war continued long after it became obviously unwinnable.
It also had a large effect on public opinion, thanks in part to the waves of protest that wracked the land. As body bags were unloaded from the transport planes and the toll of US deaths mounted into the tens of thousands, the very obvious question was "Why?" Singer Phil Ochs asked "What are you fighting for?" and no answer came.
This was a turning point. Eight times more Americans had been killed in WW2, but then FDR had successfully fooled everyone into supposing that conflict to be "good" or at least necessary (it was neither) so people gritted their teeth and did what they thought they had to. But the premise behind Vietnam was the Domino Theory, and while at the time few saw how bogus that was (communism was never going to sweep the world; it failed wherever it was tried) they did rightly sense that something was wrong with it.
So a shift began. Subsequent wars were short and small. Grenada's was over in a few days. Gulf-1 brought spectacular victory in about a week. In both, US casualties were light. Then came the new Century, and with it, seemingly a new policy; after the godsend of 9/11, the FedGov invented a new enemy called "Terror." Bush-2 declared an unending War on Terror, and was applauded by all. Well, nearly all; in Congress Ron Paul said, as usual, No. He was outvoted.
"Terror" isn't a country, or an identifiable group of hostiles with a visible command structure. If some kind of "victory" were achieved, there is nobody who might sign a surrender instrument. So if one set of malcontents is put down, the FedGov moves on to the next; and each "victory" spawns more groups, so the process - the war - never ends. It's the perfect continuous war, of which Orwell so perceptively wrote back in 1948. They can never surrender because they are nowhere and everywhere.
It doesn't matter that the FedGov's wars are unwinnable. They don't need to be won. They just need to continue, so as to feed the "Defense" industry. War, as General Butler came to grasp, is a racket.
All this is a complete inversion, of course, of the myth sustained by the FedGov and its compliant media - the MSM. We're told a strong military, armed with the latest weapons that technology can produce, is essential for our defense and that of "American interests" worldwide; another elastic phrase. It's all lies.
Government and the weapons makers are in a symbiotic relationship; the former arranges continuous wars, the manufacturers equip it to fight them and furnish money for re-election and voters in the form of employees grateful to have jobs that pay well and serve the patriotic interest. Everyone wins, in a mad, lethal merry-go-round, except the taxpayer, and those the FedGov kills and maims - and except virtually everyone, whose standard of living stagnates because of the appalling waste of money. It will continue, until the FedGov ceases to exist or until one of the wars escapes control and goes nuclear.
Such is the humongous waste of life and resources in which the "racket" results. Trump realized some of this, back in 2016, and promised to wind it down. He has been able to do little or nothing, so far. JFK, too, set out to wind down the Vietnam war; Trump is lucky not to have shared his fate. Yet.
There is no fix for this madness; while the low-level continuous war may be a recent refinement, war and government have always gone together, ever since that awful day when the latter first sullied the human race. It will end only when government ends. And that, dear reader, depends on you.