Dilip Trivedi Saturday took over as the Director General of the CRPF. Trivedi,a 1978-batch IPS officer of UP cadre,was till now serving as Special DG of the BSF at its headquarters. The biggest challenge for the force is the Left Wing Extremism and we will aim to minimise the damage on our side while inflicting as much as we can on the Naxals, Trivedi said after taking over the new assignment. The post fell vacant July 31 after Pranay Sahay retired.