The twenty-first century is increasingly an era of protracted conflict. While major twentieth century wars were presumed to have a clear beginning and end, violence and armed conflict has persisted in many regions long after interstate wars were declared over. Protracted conflicts are not fought solely between militaries, but instead by a multitude of armed groups, while civilians and cities bear the brunt of hostilities. A subset of protracted conflicts are also prolonged occupations, that is asymmetric conflicts in which a dominant actor has occupied the territory of another.