Let's be real. Korea and Vietnam were both divided with the commies. In the former case, the peninsula remains divided. In the latter, the Demwits in Congress just pulled the plug and our former client and ally was overrun. Our first Afghanistan intervention started under Carter and continued under Reagan, and contributed the downfall of the USSR, without any US troop commitment. Our second intervention was in response to bin Laden's mass-murders on US soil -- except for nitwit "truthers" who blame it on the Jews or whomever really killed OJ's ex-wife since OJ didn't do it.
We went to Afghanistan to take out Al Qaeda. Now Al Qaeda are the allies of the United States with Saudi backed jihadist forces propaganda about civilians being killed and injured by the Syrian government being repeated by our government officials ranging from Sarah Huckabee Sanders hitting the Russians to Nikki Haley hitting the Syrian government and yes even President Trump blaming Syria, Iran and Russia for creating an awful humanitarian mess in Syria.
No need to fight the Taliban tribes. Need to cut a peace deal but I think President Trump’s decision to beef up forces there is to give the Afghan government leverage in the talks.