The problem of Vietnam (a very well debated topic, mind) is one that tends to attract a lot of bad thinking. Some people say stuff like "The war wasn't winnable." Nonsense. Any war is winnable, and the United States is the best example of a country that could win any war. The question is whether you are willing to pay the price - however high, and for however long - to win. Then what Shonus said applies: we decided we couldn't pay the price necessary to win (certainly there was no political will for, say a massive escalation and invasion of North Vietnam, for example), but we kept fighting. We kept fighting for a lot of reasons, surely; one of which that there was no easy way to de-escalate the war or our involvement in it, another was the need to save face in some manner, and there are certainly others.
Uh, what does 9/11 have to do with the wars in Afghanistan and Iraq? That was orchestrated by a member of the Saudi royal family who would later hide in Pakistan and practically within sight of a major military base. Bush and Cheney would have happily attacked the middle east within a few years regardless; clearly 9/11 was a useful propaganda victory for him (since people still believe it was somehow related to his wars....), but it had no practical effect on which war he would declare.
Afghanistan was done on the excuse that it was there, with the tacit support of the Taliban, that OBL and AQ were based. Which was true in sufficient detail. There really wasn't a strategic reason to attack(/'free') Afghanistan without the 911-perpetrators, at least not since the point when the West had helped kick out Russia (and kick-start the 'insurgency' industry).
All of that being arguable.
The US invaded Afghanistan less than a month after 9/11, while the skies above New York was still thick with smoke and ash. Unless somewhat presents a significant amount of evidence as context for the view that the US invasion was in any way likely barring 9/11 or a 9/11-like attack, or that such an attack would not at a minimum look very radically different from the one we saw, it's not
arguable, it's
ridiculous.
I don't know why the desire to reify Iraq and Afghanistan as if they were the same war. The wars are so radically different that it's almost baffling. Article 5, the UN, Freedom fries, Saddam Hussein, the Taliban, the assassination of Ahmad Shah Massoud on September 9th, 2001; any of these things ring bells?
And on a topic that is at least tangentially related to the present,
opposition to the Senate Healthcare bill appears to be hardening over the recess.