New Delhi has entered into a deal for an additional four Boeing P-8I maritime patrol aircraft.

The deal will be conducted under the US government’s Foreign Military Sale (FMS) mechanism, and was originally cleared by India’s Defence Acquisition Council in July 2015, according to sources familiar with the matter.

The deal was recently approved by the cabinet committee on security (CCS) and deliveries will commence within three years.

The order for four additional P-8Is is worth approximately $1 billion, with the original 2009 order for eight aircraft pegged at US$ 2.1 billion. Boeing delivered the first P-8I to the Navy in May 2013 and deliveries were concluded in 2015. All eight aircraft are now fully operational and in use for long range anti-submarine warfare (ASW) missions and intelligence, surveillance, reconnaissance (ISR) missions in support of broad area, maritime and littoral operations.

The type has provided a much needed boost to the Navy’s maritime surveillance capability in the Indian Ocean Region.

The P-8I is an India specific variant of the P-8A Poseidon, developed for the US Navy. It retains the Raytheon APY-10 surveillance radar and Universal Aerial Refuelling Receptacle Slipway Installations (UARRSI). Specific to the P-8I is the aft-facing Telephonics APS-143C (V) 3 radar and a magnetic anomaly detector (MAD) boom in the tail.

Boeing AGM-84L Harpoon Block II missiles, Raytheon Mk 54 lightweight torpedoes and Mk-82 depth charges make up the weapon fit. Equipment provided by Indian companies includes the Identification Friend or Foe (IFF) Interrogator, Data Link 2 and fingerprinting system supplied by BEL and a Hindustan Aeronautics’ supplied IFF transponder.

The P-8I will eventually replace the Navy’s fleet of eight upgraded TU-142ME long-range patrol and anti-submarine aircraft, which are almost three decades old. The Taganrog-built Tupolev TU-142MEs were acquired in 1987-88 and used to perform anti-submarine warfare and other patrol missions.

Navy P-8Is are based NAS Rajali, which is located at Arakkonam, about 70 Km off Chennai in India’s southern state of Tamil Nadu and operated by Indian Naval Air Squadron (INAS) 312A.