SMART is a medium-range, canister-based ASW missile system that uses a lightweight torpedo as its payload. It has a range of 643 kilometers and can be launched from ships or a coastal battery. The system uses a two-way data link connected to airborne or ship-based submarine detection and identification systems.

The disparity between Pakistan's and India's naval forces makes it necessary for Pakistan to prepare for an asymmetric war at sea. India has two aircraft carriers, 12 destroyers, 12 frigates, 16 conventional attack submarines (SSK) and two nuclear ballistic missile submarines (SSBN), placing Pakistan at a significant numerical disadvantage.

That forces Pakistan to rely on asymmetric naval tactics and incentivizes the development of a sea-based nuclear arsenal to offset India's advantages.

In a May 2018 article for the Observer Research Foundation (ORF) , Abhijnan Rej notes that Pakistan's deterrence approach centers on using tactical nuclear weapons to offset India's conventional military superiority.

At sea, Rej notes that the Babur-3 SLCM is a survivable sea-based component of Pakistan's“full spectrum deterrence” concept pairing low-yield tactical nuclear weapons to strategic nuclear weapons such as the multiple independently targetable re-entry vehicle (MIRV)-capable Ababeel medium-range ballistic missile (MRBM) .

The strategy aims to blunt India's“Cold Start” doctrine, which seeks to seize Pakistani territory and forestall a possible Indian counterforce strike aimed at destroying Pakistan's nuclear arsenal.

Pakistan's new Chinese-designed submarines may indicate an emerging“threshold alliance” between China and Pakistan, with the Indian Ocean as its focal point.

In a March 2023 United States Institute of Peace report , Sameer Lalwani notes that threshold alliances are less than formal treaty alliances but more advanced than usual defense cooperation agreements.

Lalwani says threshold alliances are characterized by significant investments in dormant military capabilities that can one day be used after a critical political decision.

Such a relationship, he says, often entails capability aggregation, burden-sharing, geographic access and power projection. He notes that threshold alliances may have the same impact as nuclear latency through their ability to assure, deter or apply leverage in crisis bargaining.

Lalwani points out that the China-Pakistan military partnership has deepened significantly over the past decade, with China becoming Pakistan's leading supplier of conventional weapons, strategic platforms and high-end offensive strike capabilities.

He mentions that sharper US-China competition, India-China border skirmishes in the Himalayas and the disastrous 2021 US withdrawal from Afghanistan are all significant factors in China's push to establish overseas military bases and enhance strategic cooperation with Pakistan.

Lalwani mentions that China and Pakistan have increased the tempo and complexity of their military exercises, noting that their increasingly compatible arms supply chains and networked communications systems have allowed the two sides to aggregate their defense capabilities.

Significantly, that may be beneficial for combined China-Pakistan submarine operations in the Indian Ocean. In January 2023, Asia Times noted that the maritime region is attractive for PLA-N operations compared to the Western Pacific, which the US and Japanese navies patrol heavily.

China's naval base in Djibouti is aiding its regional operations, with Gwadar in Pakistan a potential base for Chinese submarine operations. Its hydrographic and surveillance ships and underwater drones are also increasingly present in the Indian Ocean.

These activities indicate that China is mapping the underwater terrain and passages for future submarine operations.

Sign up for one of our free newsletters

• The Daily ReportStart your day right with Asia Times' top stories
• AT Weekly ReportA weekly roundup of Asia Times' most-read stories

Additionally, China's growing presence in the Indian Ocean threatens India's sphere of influence and could compromise India's Exclusive Economic Zone (EEZ), as witnessed by China's activities vis-à-vis rival claimants in the South China Sea. Such Indian Ocean deployments may involve surveillance of Indian naval assets and ships in the Bay of Bengal and the Arabian Sea.

India's SMART missile test may mark a substantial step in plugging gaps in its ASW capabilities, given setbacks in its submarine program and a shortage of ASW-capable ships.

In a November 2023 article in the peer-reviewed Journal of Asian Security and International Affairs , K G Ramkumar and Prakash Panneerselvam note that the Indian Navy's conventional submarine fleet is aging with most ships over two decades old, necessitating a new focus on acquisition.

The Indian Navy's fifth Scorpene-class submarine Vagir is launched at the Mazagon Dock in south Mumbai, November 12, 2020. Image: Indian Navy

Ramkumar and Panneerselvam point out that India's 30-year submarine-building plan has faced delays, particularly in Projects 75 and 75I , which have impacted the timely acquisition of new boats. They also point out that India cannot design conventional submarines alone, despite its ability to build SSBNs with high indigenous content.

Moreover, Naval News reported in June 2023 that while India is building 16 ASW Shallow Water Craft corvettes, the project has faced delays due to supply chain issues, particularly in sourcing imported engines from an unspecified European country due to export-related problems of some subcomponents.

Naval News also points out that delays in sourcing the imported hull-mounted sonar and low-frequency variable depth towed array sonar from European suppliers could render the ships suboptimal for their ASW missions, which were encountered in building the larger Kamorta-class ASW corvettes.