The strategic balance in the Indian Ocean's underwater domain is undergoing a notable transformation, with Pakistan poised to outpace India in fielding submarines equipped with Air Independent Propulsion (AIP) systems by the end of the decade. This development underscores a significant shift in naval capabilities and strategic posturing in the region.
The Pakistani Navy currently operates three Agosta-90B-class submarines, also known as the Khalid class, equipped with the French-supplied MESMA (Module d’Energie Sous-Marin Autonome) AIP system. This system allows submarines to remain submerged for extended periods, significantly increasing their stealth and operational effectiveness. The MESMA system allows a submarine to remain submerged for more than 14 days.
Further bolstering its underwater capabilities, Pakistan is set to receive eight Hangor-class submarines from China, a variant of the Type 039A/B Yuan-class. These submarines will feature an advanced Stirling cycle AIP system, which provides an underwater endurance of 18 days.
The first four Hangor-class submarines are being built in China, while the remaining four will be constructed at the Karachi Shipyard & Engineering Works (KSEW) in Pakistan, demonstrating a significant technology transfer and indigenous shipbuilding capacity boost.
This agreement to supply eight Hangor-class submarines between China and Pakistan was signed in 2015. Deliveries are expected to be completed by 2028.
This acquisition will bring Pakistan's total AIP-equipped submarine fleet to eleven by 2030.
In contrast, the Indian Navy's progress in adopting AIP technology has been comparatively slower. India currently operates six Kalvari-class submarines, based on the French Scorpène design, but these initially lacked AIP capabilities.
DRDO has developed an indigenous Phosphoric Acid Fuel Cell (PAFC) based AIP system. As per the information available from DRDO, this indigenous AIP has successfully completed trials and is ready for integration into these submarines during their mid-life upgrade cycle.
The first submarine, INS Kalvari, is expected to receive the AIP retrofit by late 2027, with the remaining five following suit over subsequent years. Along with these six submarines, three more are to be fitted with this indigenous AIP technology.
Therefore, the Indian Navy will have nine AIP-equipped submarines by the completion of this upgrade program. As per media reports, the Indian Navy will be able to achieve this by 2032.
India's long-term plans include Project-75I, which envisions the construction of six additional AIP-equipped submarines. However, repeated delays and a complex procurement process mean that these submarines are not expected to join the fleet until after 2033, extending the gap in AIP capabilities compared to Pakistan.
Reports indicate that Project-75I has faced numerous setbacks, including disagreements over technology transfer and stringent liability clauses, leading to the withdrawal of several foreign bidders.
This disparity in the timeline for AIP-equipped submarine acquisition highlights a potential shift in the regional naval balance. Pakistan's rapid integration of AIP technology, facilitated by Chinese support, could provide it with a tactical advantage in terms of stealth and endurance.
The ability to remain submerged for extended durations without needing to surface for air significantly enhances a submarine's survivability, operational radius, and effectiveness in both offensive and defensive roles.
The Indian Navy's efforts to catch up involve both retrofitting existing vessels and developing new ones under Project-75I, demonstrating a commitment to indigenous technology and reducing dependence on foreign systems.
However, the inherent complexities of submarine development and technology integration mean that India will be playing catch-up in the AIP domain for the foreseeable future.
The evolving submarine capabilities of both nations will undoubtedly influence strategic calculations and naval dynamics in the Indian Ocean, a region of increasing geopolitical importance. As both countries continue to invest in their naval capabilities, the underwater domain will remain a critical area of competition and a key determinant of regional power balance.
