The Soviets made concerted efforts to address this vulnerability , such as beginning work on a 4,000 kilometer extension of the Trans - Siberian Railway , the BAM Line .
These alone were insufficient to rectify the basic weakness .
Although the Soviets made concerted efforts to address this vulnerability , such as beginning work on a 4,000 kilometer extension of the Trans - Siberian Railway , the BAM Line , these alone were insufficient to rectify the basic weakness .