I find that international actors are well-equipped to limit civilian slaughter: Intervention supporting the government decreases the likelihood that a government orders civilians killed. Intervention against the government leads to a decrease in death tolls when killing occurs. Ultimately, supportive intervention is a useful means of preventing government killing, while oppositional intervention limits its escalation once it begins.
The problem with this finding is that it doesn’t tell us what we have to do in this particular situation or if it works in this particular situation. But the idea that it doesn’t work, ever? Just a dogma.