I'm astonished that there are really people who think there are Muslims who are not violent now, but a Koran burning is the one thing that will tip them over the edge. And that includes General Petreus. As if there are Taliban fighters in the mountains with mortars and RPKs not shooting them at US soldiers, but as soon as they hear some clergyman in American torched a Koran, that's all it takes for them to pull the trigger.
If you do something offensive, and someone reacts violently. The problem is not that you did something offensive. The problem is that person thinks violence is an appropriate response to being offended.
If my exercising of my Constitutional rights provokes someone to violence, they have a problem, not me.