It’s not just an epic defeat for the United States. The fall of Kabul may serve as a bookend for the era of U.S. global power. In the nineteen-forties, the United States launched the Great Rescue to help liberate Western Europe from the powerful Nazi war machine. It then used its vast land, sea, and air power to defeat the formidable Japanese empire in East Asia. Eighty years later, the U.S. is engaged in what historians may someday call a Great Retreat from a ragtag militia that has no air power or significant armor and artillery, in one of the poorest countries in the world.
Source: Does the Great Retreat from Afghanistan Mark the End of the American Era? | The New Yorker
We have, I believe, proven again that we cannot successfully intervene in civil wars in far-flung countries in which the established governments are as corrupt and inept as those who are attempting to wrest power from them. Every country that went into Afganistan has left with mud on its face at the cost of many dollars and many lives.
This New Yorker op ed asks a cogent question. Can the U.S. survive another Vietnam-style defeat? I don’t think so. Some say the unexpected collapse of just about everything in Afganistan occurred because the U.S. was operating with bad intel. I suggest we were operating with zero intel. Did any sane official or military commander think when we went into that country in 2001 that we would be there so long, spend so much money, sacrifice so many lives, and then emerge saying, “By God, that was worth it?”
If so, how naïve they must have been, and continued to be up until this very moment.
–Malcolm
Malcolm's Round Table 
It’s a very sad and very sobering development. These sentences in the op-ed jumped out at me in particular: “For the United States, the costs do not end with its withdrawal from either Afghanistan or Iraq. It could cost another two trillion dollars just to pay for the health care and disability of veterans from those wars. And those costs may not peak until 2048…”
I agree. I suspect a lot of people think that when the troops are all home, that there’s nothing left to pay when, in fact, the payments for many soldiers are just beginning.