Why is what Colonel Joll does as far as torturing the enemy in Waiting for the Barbarians any different from how we the United States react in war?
On the one hand, you could argue that there is in fact very little difference between the abhorrent practices of Colonel Joll in his search for the truth and various incidents from the history of the United States that have involved torture of people of other nationalities. Perhaps the most important one of recent history would be the infamous use of Guantanamo Bay, where prisoners were held for months without trial and forced to lead an existence where they were stripped almost of every single human right. More recent cases would be the use of waterboarding as part of interrogation techniques. Although the sheer cruelty and physical violence of Colonel Joll is absent from such examples, the basic idea of power and its abuse is certainly evident in both cases.
However, equally, you could argue that hopefully the United States is entering more civilised times and that the country that is recognised by so many as a symbol of freedom and equality of opportunity cannot be related to a time and location that is so very different from today. If you take this view, the various excesses of Colonel Joll are shown to be the actions of a sadistic, power-obsessed individual who has very little to do with preserving freedom and the rights of the many by the taking away the rights of the few. From this viewpoint, it is impossible to compare Joll's vain actions in torturing innocents cruelly when they presented no threat to America's response to the tragedy of 9/11.