India, March 4 -- The Defence Procurement Board (DPB) on Monday cleared the Indian Air Force (IAF) proposal to buy five more S-400 air defence systems from Russia according to people familiar with the matter -- a move that comes even as West Asia is seeing a conflict dominated by ballistic missiles and kamikaze drones.

The board, headed by defence secretary Rajesh Kumar Singh, accepted the IAF proposal which will now go to the Defence Acquisition Council (DAC) headed by defence minister Rajnath Singh for acceptance of necessity (AoN).

It is only after DAC grants AoN that the cost negotiation committee will be constituted to fix the price of the new acquisition before the matter is given the final green signal by the Cabinet Committee on...