Impossible, you say? Bear in mind:
- US Marines and soldiers were accused of similar attacks in Iraq. In some cases the evidence was pretty much overwhelming, but the soldiers involved generally got off with a slap on the wrist, at worst. (Google "Haditha massacre" if you want more info.)
- One of the not-so-often cited reasons for the "success" of the "Surge" in Iraq was the use of Special Forces operations to quickly and brutally "eliminate bad guys." The general who oversaw those operations was none other than Stanley McChrystal, who was brought in by Obama to head up a "more aggressive and innovative" US military effort in Afghanistan precisely because of his effectiveness in Iraq.