The ECOWAS states have threatened military intervention to restore the democratically elected government of Niger. This market will resolve YES if there is open conflict in the region related to the coup. 

By open conflict, I mean uniformed troops conducting a significant military operation. Small operations like a Special Ops raid won't count, it needs to be a substantial deployment. It also needs to be openly conducted by one or more ECOWAS states. Secret operations or paramilitary operations will not count.

I'm leaving the "related to the coup" part intentionally a bit vague. The spirit of the question is if the instability will lead to conflict. The nature of instability is it can go a lot of ways. For instance, one can imagine scenarios where a proxy war in Niger leads to open conflict between an ECOWAS state and Mali or Burkina Faso. That scenario would still count even if Niger was not directly involved in the fighting. Basically, if an ECOWAS member is putting uniformed troops into combat by the end of the year, it will count, unless some new crisis emerges and the operation is in response to that.