There are so many reasons for not having more troops there. More targets, local resentment, force protection issues, expense, what would you do with troops that have not been trained for the type of work needed?
Most of these folks yammering about "more troops" are from the cannon fodder days. They simply don't understand that warfare has made advances beyond handing someone a gun and telling them to go out and kill the enemy.
I think the days of having huge armies is gone. With technology the way it is, I think a lean mean military is the way to go..