Consider this. Apart from the blast on the train, which killed at least 50 people, Bodo militants blew up a vital road bridge on National Highway 31, 12 hours before detonating the bomb underneath the train, in their efforts to snap links with the rest of the country. In less than 48 hours, another railway bridge, this one on a metre-gauge track leading to the interiors of Arunachal Pradesh, was damaged in another blast. The rail link on the north bank of the Brahmaputra is crucial from the army's point of view since it connects the bases which guard the border with China.