MOSCOW, January 19. /TASS/. The system of 120-km deep defensive lines increased the survivability of Russian troops in Ukraine five-six times. In eight months, over 400 battalion defensive areas were built, which is an unprecedented achievement, head of the Engineering Troops Lieutenant General Yury Stavitsky told the Krasnaya Zvezda daily.

"A highly echeloned 120-km deep system of defensive line, positions and areas was prepared by the beginning of the counteroffensive along the whole contact line. Due to the scope and time of the mission, it was an unprecedented development in the history of wars and armed conflicts. The completely fortified lines, positions and areas increased the survivability of troops and the engagement effectiveness of arms and hardware five-six times," he said.

Over 3,600 kilometers of trenches, 150,000 dugouts and hardware shelters, over 45,000 bunkers and 12,000 reinforced concrete erections were made by the beginning of the Ukrainian counteroffensive.

"Over 400 battalion defensive areas were built in eight months in difficult weather and climatic conditions and in incessant combat actions and massive hostile engagement of precision weapons and drones. The system of defensive lines, positions and areas included two-three defensive lines. To compare, the 135-km Mannerheim line was built in ten years, the 400-km long Maginot line was built in 12 years," Stavitsky said.