Your operational requirements are significantly different, so I'm told by several military folks I've talked to, none of whom attempted to play down the Afghan resolve, but simply pointed out that if we didn't care about "keeping it", we would not encounter (all of) the same difficulties Ivan did.
Ah, but since Ivan tested his superpower battlefield capabilities on lightly armed Afghans and lost thanks to US assistance, the Afghans' neighborly Pakis have come up with nukes and perhaps a few other devices obtained from hardup Soviet CBW researchers who are eager to assist the Afghans just as the US did. Nobody would dare suggest the Slavs are looking for payback, and have lulled the last remaining superpower into thinking bygones are bygones, the cold war is over and done, as if thousands of handy airliners would never become giant Stingers.