The successful underwater test firing of the K-15 Submarine Launched Ballistic Missile (SLBM) 28 January 2013 by the DRDO is a remarkable achievement, considering that only five countries possess this capability. The missile incorporates advanced technologies, which make it a reliable nuclear delivery system. The missile is to be integrated with the Indian SSBN INS Arihant, which can reportedly carry twelve such missiles.

Technical Analysis
The missile is reported to have attained an apogee of around 40 to 50 km, which is extremely depressed. This indicates two aspects. Firstly, the actual range of the missile is much more than the declared one. The range could be further increased by payload (one metric ton) trade-off. Secondly, this missile has a high probability of penetrating any missile defence system as it has some vital combinations: speed and a low trajectory. The low trajectory helps to avoid early radar detection and also may confuse the missile defence fire control algorithm from identifying it as a threat, while the hypersonic velocity reduces the reaction time of the defence systems.

The missile is reported to have achieved very high accuracy despite being launched in a relatively depressed trajectory. The underwater test launches conducted so far were done from a submerged pontoon at a depth of 50m simulating a submarine launch, which is similar to a launch from a pre-surveyed launch site on land. The geographical data fed to the Inertial Navigation System (INS) will be very precise, the only difference being that the missile had to take into count the hydrodynamics involved until it surfaces. The same missile, when launched from a SSBN on patrol, does not enjoy this advantage. Any navigational error in the SSBN navigation system will be transferred to the missiles’ onboard guidance system. This error is bound to compound as the missile travels over long distance, degrading its Circular Error Probable (CEP). This acquired error can be reduced to some extent, if in future, a GPS aided INS is used. A point to be noted here is that an error of few tens of meters does not matter much if the payload is a nuclear warhead.

Deterrence Value
The missile is reported to have a range of 700 km when launched in the conditions under which it has been tested so far. This limited range becomes a serious constraint. For example, this missile cannot reach Islamabad or Lahore even when the boat positions itself close to the Pakistani shore. The only major city that the boat can threaten from a safe distance is the port city of Karachi.

For strikes against China, the boat has to position itself inside the first island chain to get within striking distance of Shanghai. Worse, to reach within striking distance of Beijing, it has to operate in the Yellow Sea or Bohai Sea, which is close to one of the Peoples Liberation Army Navy’s (PLAN) bases, which is also a base for its submarine fleet. This will be a highly risky endeavour. Hence, as a sea based deterrent, this missile has relatively very limited value. The DRDO is also developing the K-4 SLBM that reportedly will have a maximum range of 3500km, which when deployed, will enable the submarine to operate from a longer distance to be within striking distance of the target and complete the triad in the real sense. India needs three SSBN platforms to maintain 24x7 presence of at least one submarine in the waters around China.

How does the ‘Sea based deterrence’ affect Pakistan’s nuclear equation?
Pakistan, for the past few years, has been increasing its nuclear arsenal with a focus on tactical nuclear weapons with an aim to deter any major Indian conventional offensive action. But the concept of tactical nuclear strike makes little sense because India would consider it a first strike even if it is used against Indian forces inside Pakistani territory. Hence, any Pakistani first strike ought to focus on Indian nuclear forces in an attempt to cripple India’s retaliatory capability. With the induction of sea based deterrence, this option for Pakistan could be seriously weakened. This development is bound to upset Pakistani nuclear strike calculations, and might force Pakistan to improve its Anti Submarine Warfare (ASW) capability.

The crucial point is whether India’s push towards deploying sea based deterrence will compel Pakistan to further increase its nuclear arsenal. Any increase in the nuclear arsenal beyond what Pakistan considers as required for minimum deterrence does not seem to serve any useful purpose, and this minimum deterrence estimation would have included the possibility of an Indian first strike. An increase would in no way be a counter to an Indian sea-based deterrent force. Besides, it will put an unnecessary burden on Pakistan’s already strained economy.

Conclusion
The K-15 is a good weapon in terms of technological sophistication. However, the missile’s range appears to be its only drawback even when launched in the minimum energy trajectory, where the range could be little above 1000 km. To have effective sea-based deterrence, the range of the delivery vehicle should at least be above 2000 km. Nevertheless, it is a good start and once effective sea based deterrence is in place, it certainly would tilt the balance in favour of India, at least within the subcontinent.