On a podcast some years ago, I came across a simple yet powerful litmus test to decide which side of a complicated conflict lines up with my personal values. Imagine if one side had complete and total power, what are they saying they'd do with that power? If the answer appalls you, problem solved.
Obviously, things are not always so simple. A party may outwardly state one objective but secretly have another. But, at least in the case of international conflict, you'll be surprised at how often a group's publicly stated mission goes completely against your beliefs.