This one came straight into my mind after reading your post! Shooting Dogs (2005), a really powerful film with some incredible dialogue scenes. It's set during the Rwandan genocide, in a school where UN peacekeepers are posted so they harbour Tutsi people there for their protection.

In this scene Fr. Christopher finally breaks and lashes out at the UN commander for not doing anything about the slaughter, and from it comes the title of the film so I won't ruin it in case you haven't seen... It's a great moment, a great performance, and part of a brilliant script.