New Delhi, Oct. 5 -- India is stepping up efforts to fortify the strategically vital Siliguri Corridor, popularly known as the "Chicken's Neck", with plans for underground military infrastructure, hardened command and ammunition facilities, stronger air-power capabilities and alternative connectivity routes to the Northeast.

The corridor, located in northern West Bengal, is just over 22 km wide at its narrowest point and serves as the crucial land link between mainland India and the northeastern states. Wedged between Nepal and Bangladesh, with Bhutan and China nearby, the corridor is among India's most strategically vulnerable areas.

India is planning a 40-km underground railway corridor through the Siliguri Corridor to ensure secure a...