For any government, there can only be a single worst nightmare. And that is the internal instability of their region. This instability could be due to the rebels fighting within their country, a civil war, or the rise of a terrorist organization in the land such as ISIS in Syria. Indeed, internal threats happen to be far more dangerous and difficult to deal with as compared to the external threats from other governments or an external terrorist organization.
Usually, it takes decades to solve a situation like this and in case it gets out of hand, a lot of causalities have to be faced.