Last night, at a couple of gatherings with family and friends, some people were speculating that Afghanistan could become Barack Obama's Vietnam -- or Iraq. A blogger at the socialist Monthly Review made this precise charge last summer. Should we reasonably fear this possibility?First, events since election day seem to assure that Obama's campaign promise about Iraq withdrawal will be fulfilled.Since I posted about "Obama's exit strategy?" just 10 days ago, Iraq's Parliament has approved a Status of Forces Agreement with the US establishing a formal timetable for the withdrawal of US troops....