Nearly 20 hours of talks in Minsk between the leaders of Russia, Ukraine, Germany and France over the crisis in eastern Ukraine ended with an agreement early Thursday morning . At the very least, the deal demonstrates the diplomatic will on all sides to produce an agreement after several weeks of intensified fighting between Ukrainian security forces and pro-Russia separatists. However, the evolution of the Ukrainian crisis will depend on how — or even whether — the agreement can actually be implemented. Some of the issues addressed in the deal are controversial, and others are open to interpretation, so the agreement's true significance will only become evident in the coming days and weeks. In terms of technical details, the agreement largely mirrors the cease-fire agreement signed in early September .