People who write about international politics inevitably make a lot of incorrect predictions. It is sometimes useful to look back and ask why our prognostications were wrong. At the start of this year, I asked, “Where will international stabilization forces intervene in 2015?” My best guesses were Ukraine, Nigeria, Libya and Syria.

There has been much talk about deploying peacekeepers to these war zones over the ensuing 12 months, but markedly less action. In retrospect, it seems clear that governments and international organizations have taken a cautious approach to mounting new missions in high-risk environments in 2015. But there are equally clear signs that they will not be able to resist these dodgy deployments indefinitely. ...