Ukrainian forces have taken under control two thirds of the so-called “grey security zone" in Donbass, according to Ukrainian presidential advisor and aide to the Defense Minister Yury Biryukov. The “gray zone” separates the forces of the self-proclaimed Donetsk and Lugansk People’s Republics and the Ukrainian army. The borders of the zone are defined by the Minsk agreements, and sending troops to settlements in the gray zone constitutes a violation of the deal. The Ukrainian forces have repeatedly announced taking control of new positions in the “gray zone” over the time of their military operation in Donbass, TASS said.