What is the implication of designating territorial integrity as an "eternal" constitutional principle? This article reflects on the protection of territorial integrity in the Ukrainian constitution, and especially within its provision of unamendability, against the backdrop of the 2014 Crimean crisis. It investigates the aims and limits of territorial integrity as an unamendable principle in the face of a double threat: internal in the form of a secessionist movement and external in the shape of forceful annexation of territory. The article argues that the preservative promise of unamendable territorial integrity is severely curtailed by this double vulnerability, even when backed by a constitutional court with far-reaching powers of judicial review. The article concludes that the uncertainty surrounding territorial change in constitutional law and theory is not alleviated by unamendable protections of territorial integrity.