Border Security Force (BSF) has procured Israeli tethered drones and thermal imagers to check smuggling and illegal infiltration in Dhubri sector of Assam, where a major part of the India-Bangladesh border passes through a riverine stretch, reports Eastern Mirror on November 6. The 61-km-long border in Dhubri area of western Assam, where the Brahmaputra enters Bangladesh, comprises vast chars (sand bars) and multiple river channels.