The P75I submarine deal is at its final stage and awaits a decision by the competent authority, Defence Secretary Rajesh Kumar Singh said on Thursday, adding that a proposal for additional Scorpene submarines is also under consideration.

Every one of these boats will be built in India, the Defence Secretary said in an interview, ruling out building them abroad.

P75I submarine deal awaits final decision

"Both Project-75(I) and additional Scorpene submarines are being considered. Project-75(I) is at the final stage. It has been submitted and is pending a final decision by the competent authority," he said.

Project-75(India) covers six conventional submarines fitted with Air Independent Propulsion (AIP), to be built by Mazagon Dock Shipbuilders Limited (MDL) with Germany's ThyssenKrupp Marine Systems (TKMS) under the strategic partnership model. The Defence Secretary referred to it as the programme with the Germans. The government cleared MDL to begin negotiations in August 2025, and the programme has been valued at around Rs 70,000 crore, according to reports. MDL and TKMS completed the concept design work by the end of that month, according to TKMS. The design comes from the TKMS Type 214 lineage, according to reports.

Navy field trials favoured the MDL and TKMS bid over a rival Navantia and Larsen and Toubro consortium, according to reports. Once the Ministry of Defence concludes negotiations, a deal of this size goes to the Cabinet Committee on Security for final approval. Delivery of the first boat has been projected at around seven years from contract signing, according to reports.

Two more Scorpenes under consideration

The Scorpene proposal is not as far along, the Defence Secretary said, but it remains under consideration. He spoke of two additional boats, which would also be built in India.

The Indian Navy already operates six Kalvari-class submarines, built by MDL to the French Scorpene design under Project-75 with Naval Group. The first, INS Kalvari, was commissioned in December 2017 and the sixth, INS Vagsheer, in January 2025. MDL built all six in Mumbai.

"Submarines will be entirely built in India, no doubt about it. There's no such suggestion or consideration in any case," he said.

DRDO AIP to go into a submarine at its 2027 refit

The indigenous AIP system developed by the Defence Research and Development Organisation (DRDO) is to be fitted into one of India's own submarines when it comes in for a refit towards the middle of next year, the Defence Secretary said.

AIP lets a conventional submarine stay submerged far longer without surfacing to recharge its batteries. DRDO's version is fuel cell-based and was developed by its Naval Materials Research Laboratory. The six Kalvari-class boats were built without AIP, and the DRDO plug is meant to add it through their refits.

The groundwork for that refit was laid in December 2024. The Ministry of Defence signed two contracts worth around Rs 2,867 crore in the Defence Secretary's presence that month. MDL received around Rs 1,990 crore to build the AIP plug and integrate it onboard Indian submarines, and Naval Group around Rs 877 crore to integrate the DRDO-developed Electronic Heavy Weight Torpedo on the Kalvari class. The AIP work was expected to generate nearly three lakh man-days of employment, the ministry said at the time. MDL later signed an agreement with Naval Group for technical support, proprietary components and training to integrate the DRDO system on the Kalvari class, according to reports.

NPOL combat system for the submarine fleet

DRDO's Naval Physical and Oceanographic Laboratory (NPOL) has recently developed what the Defence Secretary described as a very advanced indigenous integrated combat system for submarines. It will be fitted across the fleet over time, as each boat comes in for refit. The Kochi-based laboratory has long supplied the Navy's sonars, including the USHUS sonar fitted on its submarines. The Kalvari class currently uses Naval Group's SUBTICS combat management system.

"That will again be a major game changer when it comes to improving the combat capabilities of our submarines," he said.

Multiple lines of effort under water

"We have multiple lines of effort going on to strengthen our underwater capabilities," the Defence Secretary said, listing the AIP retrofit, the Scorpene proposal, P75I and the NPOL combat system among them.

Further out sits Project-76, the Navy's first conventional submarine to be designed in India, led by its Naval Design Bureau. Prime Minister Narendra Modi was shown a model of the design at Larsen and Toubro's Hazira complex in June. Private industry is also stepping in on underwater systems. Nibe Group and Naval Group signed a memorandum of understanding in September covering underwater drones, mine countermeasure vessels and submarine systems, and Defence Minister Rajnath Singh addressed the Navy's top commanders at the Naval Commanders' Conference in New Delhi this week.