In the aftermath of the Molotov–Ribbentrop Pact, with the westward expansion of the USSR in 1939 and 1940 into Poland, the Baltic, and Bessarabia, the decision was made to abandon the line in favour of constructing the Molotov Line further west, along the new border of the USSR. A number of Soviet generals felt that it would be better to keep both lines and to have a defence in depth, but this conflicted with the pre-World War II Soviet military doctrine.[1]