During the Great Patriotic War, production of diesel and electric locomotives was suspended; only steam locomotives were produced. After the war, some factories shifted their focus from steam to diesel and electric locomotives. In 1956, at the 20th Party Congress, it was decided to mass-produce electric and diesel locomotives and mothball steam locomotives as a strategic reserve. Two years later, imports of passenger electric locomotives from Czechoslovakia began. In 1959 the first Soviet gas turbine-electric locomotive, the model G1, was introduced.