I think NATO intervention in Kosova is a good example, as it was defined in these term. But at the same time it is controversial as the UN did not give approval for it.

You could look at the situation now and try to write if it a good move or not.

You could say either it was a good move as it helped to oust Milosevic and stopped the immediate conflict...or it was bad because it caused cracks in the NATO-Russia relationship, set precendent for future unapproved invasions (Iraq).