The border also ran along part of the length of three major rivers of central Germany: the Elbe between Lauenburg and Schnackenburg (around 95 km or 59 mi), the Werra and the Saale. The river borders were especially problematic; although the Western Allies and West Germany held that the demarcation line ran along the eastern bank, the East Germans and Soviets insisted that it was located in the middle of the river (the Thalweg principle). In practice, the waterways were shared equally but the navigation channels often strayed across the line.