The calculus of modern air defence is rapidly changing. As recent global conflicts have demonstrated, the skies are increasingly populated not just by high-end fighter jets, but by highly saturated, low-cost drone swarms and subsonic cruise missiles.
For India, this asymmetric threat is materialising rapidly across its western borders. To counter Pakistan's expanding inventory of subsonic cruise missiles and armed drones, the Defence Research and Development Organisation (DRDO) is forging a new tactical doctrine: a layered air defence grid where cutting-edge Directed-Energy Weapons (DEWs) work in tandem with kinetic interceptors like the Akash and VL-SRSAM.
The Growing Subsonic Cruise Missile Threat
Pakistan has heavily invested in a diverse portfolio of subsonic, terrain-hugging cruise missiles, most notably the Babur and Ra'ad families, which fly at approximately Mach 0.7.In the past, the rapid production of these weapons was hampered by a reliance on Ukrainian engine suppliers, such as Motor Sich.
However, that supply chain void has now been aggressively filled by local production and the integration of Chinese WS-series turbofan engines. This shift allows Pakistan to stockpile and launch mass salvos of cruise missiles designed to hug the earth and evade traditional early warning radars.
Coupled with an influx of cheap unmanned aerial vehicles (UAVs) and loitering munitions, the strategy relies on overwhelming an adversary’s air defence network through sheer volume.
The Asymmetry of Interception Economics
The primary challenge for the Indian armed forces is the economic asymmetry of interception.Firing a sophisticated kinetic surface-to-air missile (SAM), which can cost upwards of ₹15 to ₹25 lakh per shot, or an Akash interceptor costing roughly ₹2.5 crore, against a drone worth less than $70,000 creates an unsustainable attrition rate.
If an adversary launches a saturated attack involving hundreds of drones followed by dozens of cruise missiles, traditional SAM batteries could quickly run dry, leaving critical infrastructure exposed.
DRDO’s Directed-Energy Solution: From DURGA to Surya
To flip this cost-exchange ratio, DRDO is accelerating the development of high-powered laser weapons.India has successfully moved beyond early soft-kill dazzlers to the DURGA-II programme, which is developing 100 kW class solid-state fibre lasers capable of structural hard-kills against drones and rockets at ranges of about five kilometres.
However, destroying a heavily reinforced, terrain-hugging cruise missile requires significantly more thermal energy and a sustained "dwell time"—holding the laser beam on a vulnerable point, such as the missile's fuel tank or guidance sensors, for several seconds.
To achieve this, DRDO has initiated a conceptual Mk-III programme targeting a massive 300 kW power output by the end of the decade.
A 300 kW laser possesses the sheer thermal force required to melt through the airframe of a cruise missile, neutralizing it for a highly economical ₹5 to ₹10 lakh per engagement.
A Layered, Synergistic Defence Grid
Despite their revolutionary cost advantages, laser weapons are not a silver bullet. DEWs are inherently constrained by atmospheric conditions; laser beams suffer from severe attenuation in heavy rain, thick fog, and coastal humidity.Furthermore, a laser can only engage one target at a time and requires a direct line of sight, making it challenging to track terrain-hugging missiles until they are relatively close.
Because of these physical limitations, DRDO is not designing DEWs as standalone interceptors. Instead, they will act as a vital layer within a highly integrated air defence grid.
In a saturated attack scenario:
- The Laser Shield: 50 kW and 100 kW laser systems will be tasked with rapidly burning through the first wave of low-cost drone swarms, conserving expensive SAMs.
- The 300 kW Heavy Hitters: The larger 300 kW DEWs will target incoming subsonic cruise missiles, engaging them as soon as they cross the line-of-sight horizon.
- The Kinetic Backbone: Traditional interceptors like the Akash missile system, with its ramjet propulsion and 25-kilometre intercept range, along with the naval VL-SRSAM, will act as the all-weather, multi-target kinetic backup. They will intercept targets that the lasers cannot reach due to weather constraints, or mop up mass salvos that overwhelm the laser's sequential engagement rate.
By weaving directed-energy weapons into its existing kinetic arsenal, India is building a resilient, cost-effective shield tailored to the realities of modern saturation warfare.
