DRDO Hands Bharat Dynamics the Technology for 'Mohini', a Decoy Built to Save Indian Submarines

The Defence Research and Development Organisation has transferred the technology for the Submarine Fired Decoy (SFD) — codenamed Mohini — to state-owned Bharat Dynamics Limited (BDL), clearing the way for series production of a system designed to protect Indian Navy submarines from incoming torpedoes. The Transfer of Technology (ToT) agreement was signed in the third week of August 2026 by DRDO's Naval Science and Technological Laboratory (NSTL) in Visakhapatnam, and news of the deal moved BDL's stock up nearly 3.8% on August 21.

What Mohini Does

A torpedo homing in on a submarine typically tracks the acoustic and magnetic signature the submarine gives off underwater — its propeller noise, machinery hum and hull signature. The Submarine Fired Decoy is a countermeasure that a submarine launches when it detects it is under attack: the decoy emits an acoustic signal engineered to mimic the submarine's own signature, drawing the incoming torpedo away from the real target and buying the submarine time to evade.

This is a "soft-kill" approach to torpedo defence, in contrast to "hard-kill" systems that try to physically intercept and destroy an incoming torpedo before it reaches the target. Submarines typically rely on a mix of both: decoys to confuse a torpedo's guidance system, and evasive manoeuvring or counter-torpedo systems as a backup. Mohini adds an indigenous, submarine-launched option to that toolkit, reducing the Navy's reliance on imported decoy systems for a capability that is a base-level requirement on any modern submarine fleet.

NSTL's Underwater Weapons Pedigree

NSTL, based in Visakhapatnam, is DRDO's primary laboratory for underwater weapons and has developed a wide range of India's torpedoes, mines, decoys, targets and underwater fire-control systems over the past several decades. Its portfolio includes the Varunastra heavyweight anti-submarine torpedo and — jointly with the Naval Physical and Oceanographic Laboratory in Kochi — the Maareech Advanced Torpedo Defence System, a towed and expendable decoy system already inducted into Navy service. Mohini is a submarine-launched addition to that decoy family, aimed specifically at protecting India's own submarine fleet rather than surface ships.

The transfer to BDL follows a now-familiar DRDO pattern under the Atmanirbhar Bharat (self-reliant India) push: labs like NSTL develop and prove out a technology, then license it to a defence public-sector undertaking or private manufacturer for volume production, rather than manufacturing weapons systems themselves. NSTL and BDL have worked together before — the two have already delivered indigenous wire-guided heavyweight torpedoes, handed over to NSTL earlier this year at Visakhapatnam, before this latest decoy technology transfer.

Why It Matters for BDL and the Navy

For BDL — a Hyderabad-headquartered defence PSU best known for manufacturing missiles including the Akash air-defence system and Konkan/Dhanush variants of the Prithvi missile family — the SFD licence adds an underwater-systems line to a portfolio that has so far been dominated by land- and air-launched missiles. That diversification matters as the Navy's submarine fleet, including both diesel-electric boats and the indigenous nuclear-powered Arihant-class, grows and needs a steady domestic supply of consumable defensive systems like decoys, which are expended in combat and training and need to be restocked regularly.

For the Navy, an indigenous SFD supply chain reduces dependence on imported decoy rounds — historically sourced from foreign submarine-systems suppliers — for a capability that has to be manufactured and re-stocked continuously rather than procured once. It also fits into a broader push across DRDO's naval labs to indigenise the less headline-grabbing but operationally essential systems that keep a submarine fleet combat-ready, alongside the more visible efforts around new submarine classes and torpedoes.

The Broader Pattern

The Mohini transfer is one of several ToT deals NSTL has struck this year as DRDO works through a backlog of naval technologies ready to move from lab validation to industrial production. Defence Minister Rajnath Singh's ministry has been pushing DRDO labs to speed up exactly this kind of transfer, arguing that indigenous research delivers limited value to the armed forces until it is manufactured at scale and fielded. BDL's stock reaction on the news — a rise of nearly 3.8% to around ₹1,361 on August 21 — reflects investor expectations that the decoy licence will translate into steady, recurring production orders once the Navy formalises its procurement requirements.

A Crowded Order Book for BDL

The Mohini licence lands on top of an already expanding order book for BDL, which has spent much of 2026 absorbing new contracts as India accelerates missile and precision-munitions procurement — from the Army's long-range attack drone deal to broader Defence Acquisition Council clearances covering anti-drone and anti-tank systems. Layering a submarine-decoy production line onto that pipeline signals that the government sees BDL less as a single-product missile manufacturer and more as a general-purpose platform for whichever indigenous weapons and countermeasure technologies DRDO's labs finish validating, across land, air and underwater domains alike. For a company still primarily identified with the Akash system and Prithvi-derived missiles, an underwater-systems line also diversifies revenue away from programmes that are more exposed to the ebb and flow of any single service's annual procurement cycle.

Underwater Warfare's Quiet Priority

Torpedo defence rarely gets the attention that new submarines, missiles or fighter jets do, but naval planners treat it as a foundational requirement rather than an optional add-on: a submarine fleet is only as survivable as its weakest countermeasure, and decoys are consumed in both live combat and routine training exercises, unlike a missile or a hull that is built once and used for decades. That consumable nature is precisely why an indigenous, repeatable manufacturing line matters more here than it might for a one-off weapons platform — the Navy needs a steady, reliable domestic source it can draw down without depending on a foreign supplier's export approvals or production schedule. As India's submarine fleet expands with new conventional boats and further Arihant-class vessels entering service over the coming years, the quiet arithmetic of how many decoys each submarine needs in its magazine, and how fast BDL can produce them, will matter as much to the Navy's underwater posture as any single new torpedo or sonar system DRDO unveils.

Sources

• India's Naval Indigenisation Push: DRDO Transfers Submarine Decoy 'Mohini' Technology To Bharat Dynamics — Swarajya
• DRDO Transfers Submarine Fired Decoy Technology To BDL — Indian Defence News
• DRDO Licenses Submarine Decoy Tech to BDL: Stock Rises 3.8% — Whalesbook
• DRDO Submarine-Fired Decoy Technology Transferred To BDL: Key Facts — Edunovations