In late 2018 India sent its first (and so far only) SSBN (ballistic missile carrying sub) INS Arihant on its first patrol, armed with ballistic missiles. That first patrol lasted only 20 days, indicating continued problems with the older Russian designed nuclear reactor. India also has problems with its SLBMs (Submarine Launched Ballistic Missile). The current one, the K4, only has a range of 3,500 kilometers, which is insufficient to hit many targets in China. The Arihant cannot carry a missile larger than the K4 and new SSBNs must be designed and built to carry missiles with a range of 8,000 kilometers so that the SSBNs can go to sea and hide in areas close to southeast India where they would be safe from Chinese countermeasures (detection systems and SSNs assigned to find and follow Indian SSBNs and destroy them in wartime before they could launch their missiles.) The Chinese occupation of the South China Sea and setting up underwater detection systems supported by numerous ASW (anti-submarine warfare) systems (airborne, surface ships and submarines both diesel-electric and nuclear) makes the South China Sea a barrier to Indian SSBNs. Sending SSBNs to patrol in the West Pacific would require traveling around the South China Sea (east of Indonesia) to reach West Pacific patrol areas. This would limit the number of SSBNs that could carry out such patrols. It would be easier to develop an SLBM with a range of 8,000 kilometers and thus able to patrol from an Indian Ocean “bastion” (safe) patrol area and still be able to hit targets throughout China.
Currently, India is developing K5 (5,000 kilometers) and K6 (6,000 kilometers) SLBMs for the new SSBNs under construction or planned. Thus India needs a larger SSBN that can handle a larger “K8” SLBM with a range of 8,000 kilometers range to have an effective deterrent against a Chinese first strike (to destroy land-based ICBMs and bases where SSBNs with shorter range SLBMs are operating from). The shorter range SLBMs are a threat to much of China but perhaps not enough to be a true deterrent. Currently, India is only working on an S5 SSBN capable of carrying K6 SLBMs. In other words, it will be decades before India has a larger SSBN with an 8,000 kilometer range SSBN. In other words, India does not have an effective sea-based ballistic missile deterrent capability.
There is also the question of whether a sea-based ballistic missile capability is really needed. Is there really a risk that China would ever realistically plan to use a first strike. The Chinese won’t admit it but their own sea-based deterrent (which is not much better than what India has now) would mainly be to deter Russia, who is currently an ally but is historically a very active foe. This is a status that India never achieved and has never sought.
Nevertheless, Indian politicians have made a sea-based missile force a major goal and have been pursuing it for some time. It wasn’t until early 2016 that India successfully tested its new K4 SLBM under realistic conditions. This consisted of a submerged silo (like the one used in a submarine) that successfully released the missile at a realistic depth. The missile reached the surface, ignited its rocket motor and completed its ballistic flight as it was designed to do. Several more successful tests like this were required before K4 could enter service. K4 is based on the Agni 3 land-based ballistic missile, which has been in service since 2010. Both the Agni 3 and K4 have a range of 3,500 kilometers. K4 is a 20 ton, two-stage, solid fuel missile that carries a one ton warhead.
Arihant was built to carry nuclear-armed K4 or K15 ballistic missiles designed and manufactured in India. Arihant has four vertical launch tubes, which can carry twelve (three per launch tune) of the smaller K15 missiles or four larger K-4s. The Arihant is based on the Russian Charlie II sub, which it resembles. The Charlie class had eight launch tubes, outside the pressure hull, for anti-ship missiles. Arihant has a crew of 90-100 and six 533mm (21 inch) torpedo tubes in addition to the four vertical missile launch tubes.
In early 2013 the K15 missile underwent its final development test and was ready to be installed in the Arihant. This came after five years of testing and tweaking. In 2007, India announced that it had perfected the technology for launching ballistic missiles from a submerged submarine. That meant the silo design had been perfected as well. In 2008, India began a series of twelve test firings from a missile cell designed to fit into the Arihant. These test firings were not done from the Arihant but from the cell placed in the ground or underwater to simulate launch from the sub. Seven launches took place in 2008.
The seven ton K15 has a 700 kilometer range with a one ton warhead or 1,900 kilometers with a 189 kg warhead. The latter weight is sufficient to handle a nuclear warhead if India has been successful in developing warhead technology to the same point the U.S. and Russia were in the 1980s.
In late 2017 India launched Arighat, the first of four “stretched Arihant” SSBNs. These 6,000 ton boats can carry eight K4 SLBMs. India is designing a larger (13,500 ton) S5 SSBN that can carry twelve K6 SLBNs with a range of 6,000 kilometers. Still not enough and a larger SSBN will have to be designed or the S5 design modified to carry fewer (probably eight) larger (wider) “K8” SLBM. The Arighat won’t be in service until 2020, or later. The S5 SSBN will require more powerful and reliable nuclear reactors, something India has been having problems with. So did China and it had a two decade head start. The first S5 won’t be in service until the early 2030s and unless the theoretical K8 SLBM is made real and the S5 design modified to accommodate it India won’t have an effective SSBN deterrent force until the 2040s.
In early 2017 the first Indian designed and built nuclear-powered submarine, the 5,000 ton SSBN Arihant finally completed another round of tests and was declared in service. Shortly thereafter parts of the sub were flooded because, as the navy put it, someone left a hatch open (or failed to close it properly) and seawater got into the boat. It was reported that ten months of repairs were required to deal with the saltwater damage. The Arihant was eventually back in service but this mishap was another example of how difficult developing a reliable and effective SSBN force is.
Putting the Arihant into service came after three decades of planning, numerous revisions and technical failures, construction and delays in getting all systems functioning at the same time. It started when India began working on an SSN (nuclear attack sub) in the late 1980s but as work progressed it was decided to enlarge SSN design by adding a ballistic missile compartment and put all their efforts into creating an SSBN. This was a tried and true solution. Russia and China had successfully done this, following the example of the United States in the 1950s.
The first American SSBNs were the five, 6,000 ton boats of the George Washington class. These were basically Skipjack class SSNs that were enlarged to add the missile compartment (for 16 Polaris missiles.) The 3,000 ton Skipjacks were designed in the early 1950s and construction of the first one began in 1956 (and entered service in 1959). The U.S. Navy literally modified the hulls of two Skipjack SSNs under construction to accommodate the missile compartment and other less drastic changes. Thus the construction of the first American SSBN began in 1957, was launched in June 1959 and entered service at the end of 1959. Four more followed and by March 1961 five of these SSBNs were in service. They all served into the 1980s. The first American SSBN class was followed by five of the 6,900 ton Ethan Allen class, which was designed from the start as an SSBN. The first of these began construction in late 1959 and entered service in August 1961. Four more followed by January 1963. Note that the first American SSN (the Nautilus) began construction in 1952 and entered service in 1955. So the U.S. Navy went from SSN to SSBN in four years. Why has the Indian Navy taken so much longer to get it done? The problem is with the Indian system for developing military technology, which is crippled by corruption and incompetent management.
For example, Arihant was supposed to enter service before the end of 2015 but there were more unforeseen technical problems to fix. Nevertheless, Arihant was commissioned as a navy ship in August 2016 even though it had not carried out its sea trials. These commenced in late 2016 and were declared successful. When Arihant eventually carried out its first “combat cruise” (with nuclear-armed missiles) in late 2018 the sub never left the Indian Ocean and its K4 SLBMs were only a threat to some targets in southern and western China. Hitting the Chinese capital, Beijing, would require the theoretical K8 SLBM carried by the equally theoretical S5 SSBN.
Arihant was launched in 2009 but completing the sub was delayed again and again because of new problems showing up. Nevertheless, the success of Arihant led to an SSN (nuclear attack submarine) program, which is now underway. In 2015 India announced ambitious plans to build six SSNs but admits development and building will probably take at least fifteen years. One locally made nuclear sub doesn't change the balance of naval power much for India, which is already dominant in the region but it does show that India can build nuclear subs and six SSNs will make a difference. There are also two stretched Arihants are under construction and two more planned.
The first SLBM was the U.S. Polaris A1, which entered service in 1961 after about five years development. Like the K15 it was a two-stage solid fuel missile. The Polaris A1 weighed 13 tons, had a range of 2,200 kilometers and a one ton warhead. In 1972 the 29 ton Poseidon SLBM entered service with a range of 5,900 kilometers. In 1979 the 33 ton Trident I entered service with a range of 7,400 kilometers and finally the 59 ton Trident II in 1990 with a range of 12,000 kilometers. Each generation of SLBM was more reliable and accurate and could carry more warheads.
There are apparently problems with the readiness of the nuclear warheads used in the Arihant SSBNs. This has to do with security and controls over who has launch authority. This subject has not become a news item yet but it is another reason why the Arihant is not really “in service” and an effective Indian SSBN force will not be for decades.