"Afghanistan is not another Vietnam" a number of smart people told me whenever I raised that question. But signs are aplenty that it is one.
No two wars are identical, of course. Vietnam was divided into north and south with Hanoi receiving massive aids from Russia and China governing over a population that was loyal to the leadership.
Afghanistan is divided by centuries old tribal conflicts, shifting loyalties and with the Taliban an ally of sorts with Al Qaeda based more on convenience (enemy of my enemy is my friend of the moment) than on ideological convictions. Yet the government US backs, just as in the case of South Vietnam, is despised by the people.
The fundamental political realities are, therefore, similar between Vietnam and Afghanistan. In both cases the US or the "West" is backing a government that is corrupt and hated by the very people in whose name they govern.
The current Afghan leadership under Karzai is reportedly running the largest narcotics operation outside of Mexico/Colombia with the brother of the president being the drug king.
The current "democratic" election is as corrupt as any staged by former South Vietnamese leaders. Read this.
Unless Obama has a surprise exit strategy up his sleeves, Afghanistan will become a very bad nightmare for his administration. Yes, Afghanistan is becoming another Vietnam, though the scale of casualties will not be as large. But it is a black hole with no light at the end of the tunnel. Could the "West" negotiate a settlement with the Taliban? It may turn out to be the only exit strategy left, unfortunately.