Let's be clear about Afghanistan: If after 20 years, and 832,000 American troops serving there...

[EX500rider]

51. "Can anybody tell me a war that we have won since 1945?"

Well WWII was Total War with the goal being the unconditional surrender of the enemy country. The wars since then have have more limited goals and thus the question is did we meet the goal we had when the war started.

N Korea tried to conquer the South...the US & UN forces defeated that attempt which was the goal. That's a win.
The goal in Iraq 2 was to take Saddam out of power and it was achieved which is a win of that goal.
Kicking Iraq out of Kuwait was the goal in the 1st Gulf War and that was achieved, also a win.
The US did not surrender or lose to the North in Vietnam, the goal there was to help the S resist the N which we did, them losing after we gave up helping them is on them. Same in Afghanistan, neither country should have expected the US to help them forever. Them falling after the US leaves is on them. Totally defeating a outside supported insurgency with out going medieval and committing extreme war crimes is most likely not going to happen.