There is room for debate as to whether or not the United States should ever have gotten involved in Afghanistan. Even if you acknowledge (as I do) that there is a legitimate place for countries, as well as people, to help those who are suffering, we do have a most embarrassing propensity for blundering into places with little to no knowledge of the culture, to their detriment and ours.
But once there, how many times can we promise people our help, accept the sacrifices of those who put their lives and families on the line for us, then decide it's too much trouble to keep our promises—how many times can we do this and still have any friends (or integrity) at all? Ask the Hmong, ask the Kurds, ask the people of Iran, ask the Native Americans for that matter.
It's like making marriage vows and bailing when life gets difficult. Oh, wait—we do that a lot, don't we?