As India and Pakistan develop sea-based nuclear weapons, ambiguities about their intentions and capabilities will elevate uncertainty in future Indian Ocean crises. Under those conditions, some conventional naval operations could inadvertently trigger nuclear escalation.
On March 13, 2025, Pakistani and Chinese officials marked the launch of a Hangor-class submarine, the second of eight such advanced platforms that Pakistan is procuring from China. While the submarine, an export variant of China’s Yuan-class submarine, is conventionally powered, some analysts and former officials argue that Pakistan will likely equip at least some of these vessels with nuclear weapons.
Meanwhile, the Indian Navy commissioned its second nuclear-powered ballistic missile submarine (SSBN), the INS Arighaat, last August, and three months later used it to test launch the nuclear-capable K-4 submarine-launched ballistic missile (SLBM).
India and Pakistan are following in a tradition of nuclear powers basing their weapons at sea. Beginning early in the Cold War, the United States and Soviet Union placed nuclear-armed missiles and depth charges on a wide range of submarines and surface ships. Most other nuclear powers have since deployed their own nuclear weapons at sea, with France and the United Kingdom relying primarily or entirely on nuclear-powered ballistic missile submarines for their respective nuclear arsenals.
The theoretical and historical foundations for this practice, as explored in a new, free online course from the Stimson Center’s Strategic Learning initiative, stem from a perceived need to enhance a nuclear arsenal’s survivability against an adversary’s first strike, i.e., provide a survivable second-strike capability.
As the South Asian nuclear powers continue developing their own sea-based deterrents, one key issue emerging is the ambiguity surrounding their capabilities and potential operations. With the aftermath of the April 22 terror attack near Pahalgam in Jammu and Kashmir already featuring signaling in the nuclear and naval domains, the importance of clarity and stability at sea is growing increasingly evident. While limiting transparency can have deterrence benefits, there are areas where India and Pakistan could provide greater clarity to mitigate risks of misperception without undermining either state’s security.
India’s Hedging
India’s official maritime security strategy and nuclear doctrine are aligned with the traditional understanding that sea-based nuclear weapons provide a survivable second-strike capability. Though India has two adversarial nuclear-armed neighbors, only China, with its much larger and quickly expanding nuclear arsenal, could pose a serious first-strike threat to India’s arsenal. Pakistan, in turn, fears the possibility of an emerging counterforce first-strike posture from India.
Yet there are signs of a possible incongruence between India’s threat landscape and the mission and capabilities of its sea-based deterrent. The deployment of India’s first SSBN, the INS Arihant, after an attack by a Pakistan-based militant group in 2019 was perceived in Pakistan as a threatening signal. The Arihant carries the K-15 SLBM as its main weapon, which has the range to reach targets in Pakistan from the Arabian Sea but cannot reach any major targets in China without traversing through vulnerable chokepoints to approach Chinese shores. Meanwhile, India has claimed that the longer-range K-4 SLBM currently under development has near-perfect accuracy – an engineering feat that would be unnecessary for a retaliatory posture but could prove useful for counterforce first-strike purposes.
India is also now developing a submarine-launched variant of the BrahMos cruise missile and test-fired BrahMos missiles from naval platforms days after the recent Pahalgam attack. The United States has previously assessed that the BrahMos is a solely conventional weapon, but Indian media outlets and Pakistani analysts often describe it as nuclear-capable. Still other analysts predict it will be made nuclear-capable in the future, with no public clarification in any direction from government or military officials.
Pakistan’s Improvisation
There are likewise ambiguities in Pakistan’s capabilities. As Pakistan seeks to reduce the current asymmetry that exists with India in terms of naval capabilities, it has taken an unconventional path to the development of a sea-based deterrent. Because Pakistan is unlikely to obtain a nuclear-powered submarine in the near-to-medium-term, some analysts expect that it will instead use diesel-electric submarines to carry nuclear weapons at sea for the foreseeable future.
The diesel-electric Hangor-class submarines Pakistan is procuring – and the Agosta-class submarines it already possesses – will likely be used mainly for conventional missions, including anti-access and area-denial. Should Pakistan choose to also arm some of these vessels with nuclear weapons to operationalize its sea-based deterrent, adversaries would likely be unable to differentiate submarines carrying nuclear-capable missiles from those that are purely conventional.
The missile Pakistan intends to use for its sea-based nuclear deterrent, the Babur-3 sea-launched cruise missile (SLCM), is also suboptimal for such a role. Cruise missiles are less commonly used for nuclear weapons, especially at sea, due to their lighter payloads and shorter maximum ranges compared to ballistic missiles. Deployment of dual-capable cruise missiles like Babur-3 would make it harder for an adversary to determine if they are nuclear-armed.
Several years before the first Babur-3 test, Pakistan allegedly modified some of its supply of US-made Harpoon cruise missiles to be able to carry nuclear warheads. This would enable the launch of nuclear-armed missiles from Pakistan’s fleet of Western-origin ships and maritime patrol aircraft. Pakistan is also developing a new missile known as Harbah, derived from the Babur missiles, that would be deployed on surface ships. It is currently unclear if the Harbah will be nuclear-capable. Were it to be, the added possibility of Pakistani surface ships carrying dual-capable cruise missiles would greatly elevate nuclear ambiguity in the Indian Ocean.
Deterrence Through Uncertainty
Introducing ambiguity into nuclear postures is often an intentional deterrence calculation. Deterrence is based on making credible threats that if an adversary takes a certain action, there will be a costly response. One way states can make their threats more credible is through brinkmanship, or “the threat that leaves something to chance,” by introducing risks that could make the situation inadvertently spiral out of control. By deploying capabilities of unclear nature or intent, for example, a state may deter its adversary from attacking those targets and risking escalation.
The United States has long utilized ambiguity as part of its nuclear deterrence posture, including by deploying nuclear-armed SLCMs during the Cold War. Today the United States is in the midst of a debate over re-adding SLCMs to the nuclear arsenal, and the American nuclear doctrine is still based on a calculated ambiguity that leaves escalatory red lines uncertain to adversaries.
Pakistan itself may be applying similar logic in its plans for a sea-based deterrent. Pakistan’s reliance on dual-capable platforms is due to economic and technological constraints, particularly given the significant technical challenges and high costs of developing nuclear-powered submarines. But according to analysts, Pakistani strategists believe that blurring capabilities at sea can help bolster deterrence and neutralize India’s conventional naval advantage.
How It Can Go Wrong
While brinkmanship through ambiguous postures can deter an adversary, conversely, the implicit threat of inadvertent escalation may be realized. Actions such as conventional operations that target nuclear forces or deployments that are misinterpreted as nuclear signaling can lead to escalatory spirals that neither side intends.
Inadvertent escalation risks are especially great at sea, where forces are deployed in the open ocean and ships can directly engage enemy vessels carrying nuclear weapons. Most famously, during the Cuban Missile Crisis, a Soviet submarine captain misinterpreted incoming explosives as an indication that war had broken out. Only the dissent of the embarked flotilla chief of staff prevented the crew from readying the launch of a nuclear torpedo.
Similar risks are on course to emerge between India and Pakistan. Despite the vastness of the Indian Ocean, the limited range of Pakistan’s SLCMs means that any submarine carrying one would have to approach close to shore to hold Indian land targets at risk. This proximity would increase the submarine’s vulnerability to India’s quickly improving anti-submarine warfare (ASW) capabilities.
In an ASW operation, Indian naval forces would be unable to reliably determine what types of weapons a Pakistani vessel was carrying and would therefore attempt to destroy any Pakistani submarine in a crisis scenario. Given Pakistan’s own fears of an Indian disarming strike, Pakistan may respond by employing its sea-based weapons upon receiving indication of incoming Indian anti-submarine operations.
Not the Only Fish in the Sea
Strategic competition in South Asia is unique in ways that amplify the stakes at sea. India and Pakistan share a disputed maritime boundary, and both claim that their contiguous exclusive economic zones can only be entered by foreign military vessels with prior consent. The region is also heavily trafficked by commercial vessels and home to increasing deployments of military vessels, including a greater Chinese naval footprint, adding further complexity and risk.
Recent maritime issues between India and Pakistan primarily involve the arrests of fishermen caught crossing the poorly demarcated boundary, including an incident last November that culminated in an Indian Coast Guard vessel intercepting a Pakistan Maritime Security Agency ship at sea to recover apprehended fishermen. Yet there have also been a few military incidents involving naval forces since South Asia’s overt nuclearization, most notably the downing of a Pakistani maritime patrol aircraft in 1999 and the accidental collision of two warships in 2011.
Adding nuclear weapons to these increasingly crowded waters will make the potential cost of future incidents unacceptably high. While the deployment of nuclear weapons in the Indian Ocean appears inevitable, the region’s nuclear powers should take measures that will allow it to happen more safely and predictably.
Sharing the Waters
One common strategy for averting misperceptions in crises is building mechanisms for timely bilateral communication. Though some such channels do exist between India and Pakistan, they are limited and underutilized. There is a hotline between the Directors General of Military Operations, but it was not used in 2022 when India accidentally launched a BrahMos missile into Pakistani territory. Several proposals exist for deepening crisis communication links, including a potential hotline between the Directors General of Naval Operations that could be used to clarify naval operations and encounters.
Historical agreements can also serve as helpful guides for managing risks. Accidental naval encounters between the United States and the Soviet Union led to the negotiation of the Incidents at Sea Agreement, which institutionalized a set of requirements designed to prevent future encounters and created avenues for dialogue between the two navies.
India and Pakistan announced an intention to reach their own incidents at sea agreement as part of the Lahore Declaration in 1999, but it is yet to come to fruition. There are related agreements on the books, including the bilateral Agreement on Advance Notice of Military Exercises and multilateral Code for Unplanned Encounters at Sea, but their measures have not always been fully implemented during past naval incidents.
Sailing Safely
While agreements between states are the clearest path to mutual understanding, there are unilateral measures India and Pakistan can take to make naval nuclear operations safer.
Indian officials and scholars often deny the existence of a shift in nuclear doctrine and justify new developments as primarily for deterring China. But the unwillingness of officials to clarify specific developments amplifies concerns within Pakistan, driving further uncertainty and risk. By clarifying doctrines and operational intentions, India could avoid unnecessarily provoking Pakistan through misinterpreted signals without limiting the survivability or effectiveness of its sea-based deterrent.
India has done well, on the other hand, to demarcate a clear technological and organizational separation between capabilities at sea. This includes operating nuclear-armed submarines separately from the Indian Navy’s conventional fleet as part of the Strategic Forces Command and likely decommissioning nuclear-capable missiles from surface vessels. Pakistan would benefit from adopting a similar approach when its own sea-based deterrent is fully realized.
This demarcation should include not only separating and distinguishing nuclear-armed vessels from other deployed capabilities, but also ensuring that sufficient command-and-control safeguards for strategic capabilities exist onboard. This would involve breaking with past practices of allowing delegation of nuclear launch authority to field commanders by maintaining centralized, assertive control over nuclear weapons at sea. A peaceful Indian Ocean is in everyone’s interest, and the stakes of escalation are becoming too great to leave to chance.
To explore naval nuclear competition in the Indian Ocean Region in greater depth, enroll in Stimson’s free online course from the Strategic Learning Initiative.
As India and Pakistan develop sea-based nuclear weapons, ambiguities about their intentions and capabilities will elevate uncertainty in future Indian Ocean crises. Under those conditions, some conventional naval operations could inadvertently trigger nuclear escalation.
On March 13, 2025, Pakistani and Chinese officials marked the launch of a Hangor-class submarine, the second of eight such advanced platforms that Pakistan is procuring from China. While the submarine, an export variant of China’s Yuan-class submarine, is conventionally powered, some analysts and former officials argue that Pakistan will likely equip at least some of these vessels with nuclear weapons.
Meanwhile, the Indian Navy commissioned its second nuclear-powered ballistic missile submarine (SSBN), the INS Arighaat, last August, and three months later used it to test launch the nuclear-capable K-4 submarine-launched ballistic missile (SLBM).
India and Pakistan are following in a tradition of nuclear powers basing their weapons at sea. Beginning early in the Cold War, the United States and Soviet Union placed nuclear-armed missiles and depth charges on a wide range of submarines and surface ships. Most other nuclear powers have since deployed their own nuclear weapons at sea, with France and the United Kingdom relying primarily or entirely on nuclear-powered ballistic missile submarines for their respective nuclear arsenals.
The theoretical and historical foundations for this practice, as explored in a new, free online course from the Stimson Center’s Strategic Learning initiative, stem from a perceived need to enhance a nuclear arsenal’s survivability against an adversary’s first strike, i.e., provide a survivable second-strike capability.
As the South Asian nuclear powers continue developing their own sea-based deterrents, one key issue emerging is the ambiguity surrounding their capabilities and potential operations. With the aftermath of the April 22 terror attack near Pahalgam in Jammu and Kashmir already featuring signaling in the nuclear and naval domains, the importance of clarity and stability at sea is growing increasingly evident. While limiting transparency can have deterrence benefits, there are areas where India and Pakistan could provide greater clarity to mitigate risks of misperception without undermining either state’s security.
India’s Hedging
India’s official maritime security strategy and nuclear doctrine are aligned with the traditional understanding that sea-based nuclear weapons provide a survivable second-strike capability. Though India has two adversarial nuclear-armed neighbors, only China, with its much larger and quickly expanding nuclear arsenal, could pose a serious first-strike threat to India’s arsenal. Pakistan, in turn, fears the possibility of an emerging counterforce first-strike posture from India.
Yet there are signs of a possible incongruence between India’s threat landscape and the mission and capabilities of its sea-based deterrent. The deployment of India’s first SSBN, the INS Arihant, after an attack by a Pakistan-based militant group in 2019 was perceived in Pakistan as a threatening signal. The Arihant carries the K-15 SLBM as its main weapon, which has the range to reach targets in Pakistan from the Arabian Sea but cannot reach any major targets in China without traversing through vulnerable chokepoints to approach Chinese shores. Meanwhile, India has claimed that the longer-range K-4 SLBM currently under development has near-perfect accuracy – an engineering feat that would be unnecessary for a retaliatory posture but could prove useful for counterforce first-strike purposes.
India is also now developing a submarine-launched variant of the BrahMos cruise missile and test-fired BrahMos missiles from naval platforms days after the recent Pahalgam attack. The United States has previously assessed that the BrahMos is a solely conventional weapon, but Indian media outlets and Pakistani analysts often describe it as nuclear-capable. Still other analysts predict it will be made nuclear-capable in the future, with no public clarification in any direction from government or military officials.
Pakistan’s Improvisation
There are likewise ambiguities in Pakistan’s capabilities. As Pakistan seeks to reduce the current asymmetry that exists with India in terms of naval capabilities, it has taken an unconventional path to the development of a sea-based deterrent. Because Pakistan is unlikely to obtain a nuclear-powered submarine in the near-to-medium-term, some analysts expect that it will instead use diesel-electric submarines to carry nuclear weapons at sea for the foreseeable future.
The diesel-electric Hangor-class submarines Pakistan is procuring – and the Agosta-class submarines it already possesses – will likely be used mainly for conventional missions, including anti-access and area-denial. Should Pakistan choose to also arm some of these vessels with nuclear weapons to operationalize its sea-based deterrent, adversaries would likely be unable to differentiate submarines carrying nuclear-capable missiles from those that are purely conventional.
The missile Pakistan intends to use for its sea-based nuclear deterrent, the Babur-3 sea-launched cruise missile (SLCM), is also suboptimal for such a role. Cruise missiles are less commonly used for nuclear weapons, especially at sea, due to their lighter payloads and shorter maximum ranges compared to ballistic missiles. Deployment of dual-capable cruise missiles like Babur-3 would make it harder for an adversary to determine if they are nuclear-armed.
Several years before the first Babur-3 test, Pakistan allegedly modified some of its supply of US-made Harpoon cruise missiles to be able to carry nuclear warheads. This would enable the launch of nuclear-armed missiles from Pakistan’s fleet of Western-origin ships and maritime patrol aircraft. Pakistan is also developing a new missile known as Harbah, derived from the Babur missiles, that would be deployed on surface ships. It is currently unclear if the Harbah will be nuclear-capable. Were it to be, the added possibility of Pakistani surface ships carrying dual-capable cruise missiles would greatly elevate nuclear ambiguity in the Indian Ocean.
Deterrence Through Uncertainty
Introducing ambiguity into nuclear postures is often an intentional deterrence calculation. Deterrence is based on making credible threats that if an adversary takes a certain action, there will be a costly response. One way states can make their threats more credible is through brinkmanship, or “the threat that leaves something to chance,” by introducing risks that could make the situation inadvertently spiral out of control. By deploying capabilities of unclear nature or intent, for example, a state may deter its adversary from attacking those targets and risking escalation.
The United States has long utilized ambiguity as part of its nuclear deterrence posture, including by deploying nuclear-armed SLCMs during the Cold War. Today the United States is in the midst of a debate over re-adding SLCMs to the nuclear arsenal, and the American nuclear doctrine is still based on a calculated ambiguity that leaves escalatory red lines uncertain to adversaries.
Pakistan itself may be applying similar logic in its plans for a sea-based deterrent. Pakistan’s reliance on dual-capable platforms is due to economic and technological constraints, particularly given the significant technical challenges and high costs of developing nuclear-powered submarines. But according to analysts, Pakistani strategists believe that blurring capabilities at sea can help bolster deterrence and neutralize India’s conventional naval advantage.
How It Can Go Wrong
While brinkmanship through ambiguous postures can deter an adversary, conversely, the implicit threat of inadvertent escalation may be realized. Actions such as conventional operations that target nuclear forces or deployments that are misinterpreted as nuclear signaling can lead to escalatory spirals that neither side intends.
Inadvertent escalation risks are especially great at sea, where forces are deployed in the open ocean and ships can directly engage enemy vessels carrying nuclear weapons. Most famously, during the Cuban Missile Crisis, a Soviet submarine captain misinterpreted incoming explosives as an indication that war had broken out. Only the dissent of the embarked flotilla chief of staff prevented the crew from readying the launch of a nuclear torpedo.
Similar risks are on course to emerge between India and Pakistan. Despite the vastness of the Indian Ocean, the limited range of Pakistan’s SLCMs means that any submarine carrying one would have to approach close to shore to hold Indian land targets at risk. This proximity would increase the submarine’s vulnerability to India’s quickly improving anti-submarine warfare (ASW) capabilities.
In an ASW operation, Indian naval forces would be unable to reliably determine what types of weapons a Pakistani vessel was carrying and would therefore attempt to destroy any Pakistani submarine in a crisis scenario. Given Pakistan’s own fears of an Indian disarming strike, Pakistan may respond by employing its sea-based weapons upon receiving indication of incoming Indian anti-submarine operations.
Not the Only Fish in the Sea
Strategic competition in South Asia is unique in ways that amplify the stakes at sea. India and Pakistan share a disputed maritime boundary, and both claim that their contiguous exclusive economic zones can only be entered by foreign military vessels with prior consent. The region is also heavily trafficked by commercial vessels and home to increasing deployments of military vessels, including a greater Chinese naval footprint, adding further complexity and risk.
Recent maritime issues between India and Pakistan primarily involve the arrests of fishermen caught crossing the poorly demarcated boundary, including an incident last November that culminated in an Indian Coast Guard vessel intercepting a Pakistan Maritime Security Agency ship at sea to recover apprehended fishermen. Yet there have also been a few military incidents involving naval forces since South Asia’s overt nuclearization, most notably the downing of a Pakistani maritime patrol aircraft in 1999 and the accidental collision of two warships in 2011.
Adding nuclear weapons to these increasingly crowded waters will make the potential cost of future incidents unacceptably high. While the deployment of nuclear weapons in the Indian Ocean appears inevitable, the region’s nuclear powers should take measures that will allow it to happen more safely and predictably.
Sharing the Waters
One common strategy for averting misperceptions in crises is building mechanisms for timely bilateral communication. Though some such channels do exist between India and Pakistan, they are limited and underutilized. There is a hotline between the Directors General of Military Operations, but it was not used in 2022 when India accidentally launched a BrahMos missile into Pakistani territory. Several proposals exist for deepening crisis communication links, including a potential hotline between the Directors General of Naval Operations that could be used to clarify naval operations and encounters.
Historical agreements can also serve as helpful guides for managing risks. Accidental naval encounters between the United States and the Soviet Union led to the negotiation of the Incidents at Sea Agreement, which institutionalized a set of requirements designed to prevent future encounters and created avenues for dialogue between the two navies.
India and Pakistan announced an intention to reach their own incidents at sea agreement as part of the Lahore Declaration in 1999, but it is yet to come to fruition. There are related agreements on the books, including the bilateral Agreement on Advance Notice of Military Exercises and multilateral Code for Unplanned Encounters at Sea, but their measures have not always been fully implemented during past naval incidents.
Sailing Safely
While agreements between states are the clearest path to mutual understanding, there are unilateral measures India and Pakistan can take to make naval nuclear operations safer.
Indian officials and scholars often deny the existence of a shift in nuclear doctrine and justify new developments as primarily for deterring China. But the unwillingness of officials to clarify specific developments amplifies concerns within Pakistan, driving further uncertainty and risk. By clarifying doctrines and operational intentions, India could avoid unnecessarily provoking Pakistan through misinterpreted signals without limiting the survivability or effectiveness of its sea-based deterrent.
India has done well, on the other hand, to demarcate a clear technological and organizational separation between capabilities at sea. This includes operating nuclear-armed submarines separately from the Indian Navy’s conventional fleet as part of the Strategic Forces Command and likely decommissioning nuclear-capable missiles from surface vessels. Pakistan would benefit from adopting a similar approach when its own sea-based deterrent is fully realized.
This demarcation should include not only separating and distinguishing nuclear-armed vessels from other deployed capabilities, but also ensuring that sufficient command-and-control safeguards for strategic capabilities exist onboard. This would involve breaking with past practices of allowing delegation of nuclear launch authority to field commanders by maintaining centralized, assertive control over nuclear weapons at sea. A peaceful Indian Ocean is in everyone’s interest, and the stakes of escalation are becoming too great to leave to chance.
To explore naval nuclear competition in the Indian Ocean Region in greater depth, enroll in Stimson’s free online course from the Strategic Learning Initiative.
