Here we go again, just as in Vietnam. Read this article.
The US military is calling for more troops to be sent in Afghanistan. Without it, the military predicts failure.
I don't blame the military. When the going is not well, they will always call for more troops. You can easily conclude that the enemy is stronger than you and therefore you need more help.
Stronger does not mean the "other" side has more troops or more fire power. It means the objective in Afghanistan of securing the country for your own military and political is beyond your capability given the level of troops.
Question is this: how much more is enough? That's the central issue in the logic of escalation. It is a moving target.
US's Vietnam effort failed for similar reasons. The objective of turning the country in favor of the US/Saigon alliance was beyond the capability of the US. Why was that has been the subject of many many books.
Unless you can win the hearts and minds of the people you want the help, over time the war becomes unacceptable to any civilized people.
Remember that famous interview by a CBS TV reporter with a marine who had just torched a Vietnamese village: "Sir, we need to burn down this village in order to save it."
If the Afghan tribes are not risking their lives to support the West in their own country and are instead giving aid and comfort to Taliban and Al Qaeda, however reluctantly, the ending of this tired old movie is a sad and a predictable one.
Afghanistan was not called the burial place of empires for nothing.