The Border Security Force (BSF) is India's border guarding organisation at its borders with Pakistan and Bangladesh. It is one of the five Central Armed Police Forces (CAPF) of India, and was raised in the wake of the Indo-Pakistani War of 1965 "for ensuring the security of the borders of India and for related matters".

It has various active roles during an outbreak of war. CAPF facilitates a navy, air wing and an artillery regiment. It is under the control of the Ministry of Home Affairs. However, the BSF has a small force of officers or "Cadre". The BSF has grown from 25 battalions in 1965, to 192 battalions with a sanctioned strength of 270,000 personnel including an expanding air wing, navy, an artillery regiment and specialized units. It is currently the world's largest border security force. BSF has been termed the First Line of Defence of Indian territories.